Mach-Lee
Well-Known Member
- First Name
- Lee
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- Jul 16, 2021
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- Vehicles
- 2022 Mach-E Premium AWD
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- Sci/Eng

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- #1
Information on the new heat pump has now been published. It is a vapor injection heat pump which means it's capable of operating at low ambient conditions. In short, the new heat pump system is very complicated. It can operate in 8 different modes. You have to marvel at the complexity—they probably spent several years designing, testing, and programing this. The underhood coolant piping and refrigerant lines have been completely redesigned to accommodate the heat pump. To support operations at low temperatures and enhance efficiency, the condenser coil had to be made much larger. Rather than sitting vertical, it now sits on a slant in order to fit under the hood (Tesla also does this). The frunk had to be shrunk in order to accommodate the large condenser coil below it.
The heat pump adds a new module called the heat pump valve control module (HPVCM), this is necessary to control THREE electronic expansion valves (EEVs) that can precisely control refrigerant flow. Also added are two cyclonic liquid gas separator valves, and a large suction accumulator. All this ensures the system can run efficiently and without liquid slugging the compressor through a wide range of operating conditions. A water cooled condenser has also been added, this is what will allow heat transfer from refrigerant to coolant for heating the cabin and battery. The new heat pump valve module, water cooled condenser, and accumulator has been located on the right side engine bay next to the A/C compressor. The battery coolant chiller that was previously in this location was moved on top of the cooling module air dam.
The 5 kW PTC heater is still present in the loop, this is a good thing because it means heat can be obtained from both the heat pump and the resistive heater. At low ambient conditions, the resistive PTC heater will take over since the heat pump output will be diminished. Unfortunately there is no information about the minimum operating temperature of the heat pump.
The design of the HVAC module behind the dash seems mostly unchanged. Liquid heater core and refrigerant evaporator like before. The only new mention I see is the ability to shut off the passenger footwell air vent when a passenger is not detected.
The cooling piping system has been repacked, but still maintains the same dual 5-way valve setup and 4x coolant pumps (one less on non-GTs) as the previous model year. (See this article for more information on the operation of the 5-way valves.) In theory, the system should allow heat transfer to and from pretty much any component in the system.
Service information (note, there are some errors):
Overall coolant and refrigerant piping diagram:
Heat pump assembly
Heat pump valves
Heat Pump Architecture
Vapor Injection Heat Pump (VIHP) System 8 Modes of Refrigerant Operation
The vapor injection heat pump (VIHP) system is a refrigerant system that provides both cooling and heating as needed throughout the vehicle using a heat pump valve unit that has a series of valves to control the temperature, pressure and direct the refrigerant flow according to the operation mode. The VIHP system provides cabin cooling by using the refrigerant cycle with a condenser (outside heat exchanger OHX) and an evaporator inside the HVAC climate control housing.
For cabin heating, the condenser (outside heat exchanger OHX) operation acts as an evaporator to absorb heat from the air, and the refrigerant to coolant water cooled condenser (WCC) is used to transfer heat from the refrigerant to the coolant. The coolant then passes through the heater core inside the HVAC climate control housing. A cabin coolant heater is also used to warm the coolant and provide heat to the cabin when requested.
Correct operation of the vapor injection heat pump (VIHP) system is highly dependent on the proper amount of refrigerant oil and refrigerant that is in the system.
Below are the 8 modes of the refrigerant system operation and the component that are used to achieve each of the 8 modes.
NOTE: The following diagrams show the refrigerant system state in each component.
(Cabin Cooling)
When cabin cooling is requested, the ACCM engages the refrigerant compressor and pumps refrigerant through the Water-Cooled Condenser (WCC) to the fully open vehicle injection heat pump heating expansion valve (HEXV), bypassing the heating liquid gas separator (HLGS) valve. The pressure and temperatures are measured by a pressure and temperature sensor "A", reporting to the PCM and vehicle injection heat pump compressor outlet temperature sensor, reporting to the HPVCM . These pressure and temperatures values are networked to the SOBDMC.
The refrigerant is routed to the condenser (aka the outside heat exchanger). The refrigerant condenses from a high pressure, high temperature gas to a high-pressure lower temperature liquid as it passes through the condenser.
The vapor injection heat pump low side refrigerant shut off valve (SOV) is closed as is the vapor injection heat pump battery chiller expansion valve (BCEXV) and the vapor injection heat pump cooling expansion valve (CEXV) opening percentage is controlled by monitoring the vapor injection heat pump outside heat exchanger outlet temperature. The vapor injection heat pump outside heat exchanger outlet temperature reports the refrigerant line temperature to the HPVCM . The HPVCM send a network message to the SOBDMC.
The refrigerant is routed through the vapor injection heat pump cooling liquid gas separator (CLGS) valve. To provide improved performance (typically above ambient temperatures of 68 °F/ 20°C) the CLGS opens to separate the high-pressure vapor/liquid refrigerant and provides vapor injection to the refrigerant compressor. The liquid refrigerant out of the CLGS continues to the evaporator on to the accumulator and back to the refrigerant compressor, in a closed refrigerant loop. The refrigerant temperature are measured by the vapor injection heat pump evaporator outlet temperature sensor, reporting to the HPVCM and network messaged to SOBDMC.
(Cabin Cooling and Battery Cooling)
When cabin cooling and battery cooling are requested, the operation for the cabin cooling operation remains the same as in cabin cooling. What is added to the system is cooling for the battery. The battery expansion valve (BEXV) is controlled by the high voltage battery coolant cooler outlet refrigerant superheat temperature that is determined by the refrigerant pressure and temperature sensor C that is reporting those values to the SOBDMC.
The refrigerant flows through the high voltage battery coolant cooler, which transfers cooling from the refrigerant to the vehicles coolant. The LIN controlled water pump is commanded on along with the 5 port valve is commanded to open the batter cooling system port, circulating the coolant through the high voltage battery cooling plate.
(Battery Cooling)
When battery cooling is requested without cabin cooling, the operation for the battery cooling operation remains the same as in cabin cooling and battery cooling , without cabin cooling portion of operation. The difference is the vapor injection heat pump cooling expansion valve (CEXV) and the vapor injection heat pump low side refrigerant shut off valve (SOV) are commanded to the off position, blocking refrigerant from entering the evaporator. The refrigerant is also routed to the TXV with shut off valve (SOV) to the high voltage battery coolant cooler that has a auxiliary chiller that transfers cooling to the coolant of the high voltage battery. The the 5 port valve is commands 100% of the coolant through the high voltage battery coolant cooler to the high voltage battery cooling plate, cooling the high voltage battery.
(Cabin Reheat)
When cabin reheat for ambient temperature greater than 68 degrees, occurs when the cooling load is high while the reheat load is relatively low. The electric water pump for the coolant heating circuit circulates coolant through the water cooled condenser (WCC) and then on through the activated high voltage cabin coolant heater. The coolant is routed through the heater core, raising the cabin temperature. The 5 port valve routes the coolant back to the electric coolant pump completing the coolant loop.
If the battery temperature is low, the 5 port valve can divert coolant through the coolant reservoir and the LIN controlled electric battery coolant pump flows coolant to the high voltage battery cooling plate to warm the battery arrays in the high voltage battery. Based on battery temperatures the 5 port valve regulates the coolant flow to control the high voltage battery temperatures.
The refrigerant from the refrigerant compressor passes through the water cooled condenser (WCC), vapor injection heat pump heating electronic expansion valve (HEXV), vapor injection heat pump heating liquid gas separator (HLGS) valve and directly on to the condenser (outside heat exchanger (OHX). The water cooled condenser (WCC) and condenser (outside heat exchanger (OHX) function as a condenser with refrigerant exiting as a high-pressure liquid.
The vapor injection heat pump low side refrigerant shut off valve (SOV) is closed and the liquid refrigerant is routed to the vapor injection heat pump cooling liquid gas separator (CLGS) valve. The percentage of the CLGS opening, controls the condenser (outside heat exchanger (OHX) temperature (subcooling) to meet the evaporator temperature sensor temperature target. Both the HLGS and the CLGS remain fully open in reheat mode and there is no vapor injection.
(Cabin Dehumidification )
The cabin dehumidification - 32°F to 68°F (0°C to 20°C) occurs when the cooling load is relatively low, while the reheat load is relatively high. During this mode the vapor injection heat pump system maintains the set temperature and regulates the cabin temperature by controlling the vapor injection heat pump cooling liquid gas separator (CLGS) valve for the condenser (outside heat exchanger (OHX) (with a lower limit to fully open) as well as the vapor injection heat pump heating electronic expansion valve (HEXV) for the water cooled condenser (WCC) outlet temperature. The refrigerant that enters the evaporator removes the moisture form the air passing over the fins to provide cabin dehumidification. Just like cabin reheat, vapor injection is not enabled in the dehumidification mode and both the CLGS and HLGS are fully open to allow free flow of the refrigerant.
The coolant circuit gains heat by passing through the WCC and the high voltage cabin coolant heater is activated if needed to provide additional heat to the coolant. The refrigerant compressor is engaged and the refrigerant exits the compressor and passes through the WCC. The refrigerant condenses and provides some heat to the coolant circuit.
The refrigerant leaves the WCC and passes through the HEXV, this is controlled for sub cool out of the WCC, then onto the condenser (outside heat exchanger (OHX). The condenser functions as an evaporator, absorbing heat from the ambient air.
(Cabin Heating)
When the system is operating in cabin heating mode, the operation is the same as cabin reheating mode 4. The LIN controlled electric water pump for coolant heating circuit circulates coolant through the water cooled condenser (WCC) and then through the activated high voltage cabin coolant heater. The heated coolant flows though the heater core to raise the cabin temperature. The 5 port valve routes the coolant back to the electric water pump to complete the heating loop.
If the battery temperature is low, the 5 port valve is controlled to open a coolant loop through the coolant reservoir and is circulated by the LIN battery coolant pump motor. The coolant flows though the battery cooling plate (in this instance heating plate) to warm the cell arrays in the high voltage battery. The high voltage battery temperature is monitored and the 5 port valve is controlled to regulate coolant flow controlling the battery temperature.
The refrigerant cycles from the refrigerant compressor through the vapor injection heat pump heating liquid gas separator (HLGS) valve , to the condenser (outside heat exchanger (OHX), through the vapor injection heat pump low side refrigerant shut off valve (SOV) and back to the accumulator before completing the refrigerant loop back at the refrigerant compressor as it does during thee deicing mode. The system uses pressure and temperature sensor inputs from the pressure and temperature sensor C, pressure and temperature sensor A, vapor injection heat pump compressor outlet temperature sensor and vapor injection heat exchanger outlet temperature sensor.
(Cabin Heating Plus Battery Cooling)
The operation for cabin heating plus battery cooling is the same as cabin heating mode 6, with the exception to the 5 port high voltage battery diverter valve shutting off heated coolant going to the high voltage battery cooling plate.
The LIN controlled electric water pump for coolant heating circuit circulates coolant through the water cooled condenser (WCC) and then through the activated high voltage cabin coolant heater. The heated coolant flows through the heater core to raise the cabin temperature. The 5 port valve routes the coolant back to the electric water pump to complete the heating loop.
If the battery temperature is high, the 5 port high voltage battery diverter valve is controlled to block the coolant from entering the high voltage battery coolant loop. The vapor injection heat pump battery chiller electronic expansion valve (BCEXV) opens in the refrigerant loop with the compressor circulating refrigerant to the high voltage battery coolant cooler. The chilled battery coolant is circulated by the LIN controlled electronic high voltage battery coolant pump through the high voltage battery cooling plate to cool the cell arrays in the high voltage battery.
(Deicing)
If the condenser (outside heat exchanger (OHX) externally freezes from the moisture in the air and ices up, the vehicle injection heat pump heating expansion valve (HEXV) opens up partially to allow refrigerant to warm the condenser (OHX) to defrost it. The vapor injection heat pump cooling expansion valve (CEXV) and vapor injection heat pump battery chiller electronic expansion valve (BCEXV) close during deicing and allows time for heat to be absorbed into the condenser (OHX). The active grill shutters remain closed with the cooling fan turned off during deicing mode. This prevents airflow from further cooling the condenser (OHX). The hot gas cycle allows the refrigerant to cycle tin a closed loop from the heat pump valve unit, to the condenser (OHX), through the open vapor injection heat pump low side refrigerant shut off valve (SOV), to the accumulator and then back to the refrigerant compressor. The pressure and temperature sensors are used to monitor the refrigerant during this refrigerant cycle.
Driver Focus Mode Feature ( if equipped)
The driver focus mode feature shuts off the air flow to the front passenger floor duct (footwell) when it is determined that front passenger seat is not occupied by utilizing front passenger occupancy seat sensor. When activated though the center display screen (touchscreen) the HVAC systems receives a network message that the front passenger seat occupancy seat sensor and then the front passenger footwell vent door actuator closes forcing fresh warm or cold air to focus the driver area demanding temperature cabin comfort.
Accumulator
The suction accumulator is designed to remove moisture from the refrigerant and to prevent any liquid refrigerant that may not have been vaporized in the evaporator core from reaching the refrigerant compressor. The refrigerant compressor is designed to pump refrigerant vapor only, as liquid refrigerant does not compress and can damage the refrigerant compressor. The suction accumulator is designed to remove moisture from the refrigerant and to prevent any liquid refrigerant that may not have been vaporized in the evaporator core from reaching the refrigerant compressor. The refrigerant compressor is designed to pump refrigerant vapor only, as liquid refrigerant does not compress and can damage the refrigerant compressor.
Heat Pump Valve Control Module
The HPVCM controls the operation of the vapor injection heat pump system. It uses inputs from other modules such as the HVAC control module, PCM and SOBDMC, to determine the percentage to open the expansion valves. It also communicates information, such as the heat pump mode, to other modules in the vehicle.
Heat Pump Valve Unit
The heat pump valve unit is comprised of various heat pump components that distributes refrigerant to the heat pump system. The heat pump valve unit consists of the following components.
High Voltage Battery Coolant Diverter Valve
The high voltage battery coolant diverter valve is a 5 port valve that controls coolant flow in the high voltage battery and cabin heater loops. The heater loop can be isolated from the battery circuit to provide max cabin heater performance, or the loops can be combined in series to provide battery heating.
These components are in the cabin heater loop.
The vehicle is equipped with a refrigerant electric compressor and an ACCM , which are integral to each other. They cannot be removed or serviced separately. The ACCM has both low voltage and high voltage connections. The ACCM requires a 12 volt low voltage system operating voltage between 9 and 16 volts. The ACCM also requires high voltage system range between 110 and 422 volts. When the ACCM receives the A/C request message, it engages the refrigerant electric compressor. The refrigerant compressor purpose is to compress a low-pressure gas refrigerant to a high pressure, high temperature gas, creating a vapor compression cycle. The refrigerant compressor has the traditional suction and discharge ports. It has an additional third port for vapor injection allowing for a vapor injection cycle. A vapor injection cycle is an enhanced vapor compression cycle with a mid-pressure injection port which allows higher refrigerant mass flows. This increases efficiency through the full operating range and allows the heat pump to operate over a wider range of ambient temperatures compared to a normal heat pump. Instead of cycling ON and OFF like a traditional compressor, the refrigerant compressor speeds up or slows down as required and the compressor may run when the climate control is off to provide cooling to the battery. For the appropriate refrigerant and refrigerant oil, REFER Specifications.
Refrigerant Pressure and Temperature Sensor A
The Pressure and Temperature Sensor A monitors the pressure and temperature of the refrigerant as it is routed from the water-cooled condenser. This is a combined sensor, and the probe sits directly in the refrigerant flow. The temperature and pressure readings are monitored by the PCM and SOBDMC . This pressure and temperature sensor is part of the heat pump valve unit and is not serviced separately from the unit.
Refrigerant Pressure and Temperature Sensor C
The Pressure and Temperature Sensor C monitors the pressure and temperature of the refrigerant as it is routed from the water-cooled condenser. This is a combined sensor, and the probe sits directly in the refrigerant flow. The temperature and pressure readings is monitored by the SOBDMC . If this pressure and temperature sensor is being replaced, it should not be removed unless the refrigerant system has been successfully evacuated.
Vapor Injection Heat Pump Battery Chiller Electronic Expansion Valve (BCEXV)
When commanded by the HPVCM , the electronically controlled Battery Chiller Electronic Expansion Valve (BEXV) decreases the refrigerant pressure downstream of the BEXV. This allows refrigerant to flow to the high voltage battery coolant cooler to cool the high voltage battery.
This is not serviceable part. It is part of the Heat pump valve unit and is replaced with the unit.
Vapor Injection Heat Pump Cooling Electronic Expansion Valve (CEXV)
The CEXV is an electronically controlled expansion valve. When commanded by the HPVCM , the refrigerant pressure is decreased downstream of the CEXV. The CEXV can be commanded fully open to allow refrigerant to pass without changing the pressure.
This is not serviceable part. It is part of the Heat pump valve unit and is replaced with the unit.
Vapor Injection Heat Pump Heating Electronic Expansion Valve (HEXV)
The HEXV is an electronically controlled expansion valve. When commanded by the HPVCM , the HEXV starts to close from the fully open position so that the refrigerant pressure upstream of the HEXV increases. The increase in pressure, increases the temperature of the refrigerant as well, because the coolant is at a lower temperature than the refrigerant, heat transfer from the water cooled cooler WCC to the coolant occurs. If not activated, the HEXV stays fully open to allow the refrigerant to pass without changing the refrigerant pressure.
This is not serviceable part. It is part of the Heat pump valve unit and is replaced with the unit.
Vapor Injection Heat Pump Cooling Liquid Gas Separator (CLGS) Valve
The Cooling Liquid Gas Separator (CLGS) valve operates in the same way as the heating liquid gas separator (HLGS) valve. It separates vapor refrigerant and feeds it back to the vapor injection port on the refrigerant compressor. Liquid refrigerant exits the CLGS and goes to the internal evaporator where it changes state from a low-pressure liquid to a low-pressure gas, absorbing heat and providing cool air to the cabin.
This is not serviceable part. It is part of the Heat pump valve unit and is replaced with the unit.
Vapor Injection Heat Pump Heating Liquid Gas Separator (HLGS) Valve
Liquid Gas separators are required to achieve vapor injection. Two phase (liquid and vapor) refrigerant enters the HLGS from the heating electronic expansion valve. The internal design of the liquid gas separator creates a cyclone which separates vapor refrigerant from liquid. The vapor is then routed back to the vapor injection port on the refrigerant compressor. At the same time, the two-phase refrigerant exits the HLGS and passes on to the condenser (Outside Heat Exchanger (OHX)) where it evaporates and absorbs heat from the environment.
This is not serviceable part. It is part of the Heat pump valve unit and is replaced with the unit.
Vapor Injection Heat Pump Compressor Outlet Temperature Sensor
This is a temperature sensor that is affixed to the refrigerant line. I measures the temperature of the refrigerant coming out of the refrigerant compressor.
Part of the refrigerant line Not serviceable part.
Vapor Injection Heat Pump Evaporator Outlet Temperature Sensor
This is a temperature sensor that is affixed to the refrigerant line. I measures the temperature of the refrigerant coming out of the evaporator.
Part of the refrigerant line Not serviceable part.
Vapor Injection Heat Pump Outside Heat Exchanger Outlet Temperature Sensor
This is a temperature sensor that is affixed to the refrigerant line. It measures the temperature of the refrigerant coming out of the condenser (outside heat exchanger (OHX)).
Part of the refrigerant line Not serviceable part.
Vapor Injection Heat Pump Low Side Refrigerant Shut Off Valve
This is a simple solenoid valve that is used to allow flow from the outside heat exchanger to the accumulator, bypassing the evaporator and chiller circuit when the heat pump is operating in heating or de-icing modes. In all other modes it remains closed.
This is not serviceable part. It is part of the Heat pump valve unit and is replaced with the unit.
Water Cooled Condenser (WCC)
The water cooled condenser (WCC) is a heat exchanger. It works by cooling down the refrigerant by removing the heat from the refrigerant vapor and transferring it to the coolant that is routed through the WCC. The coolant is fed to the heater core inside the HVAC case to provide heat to the cabin and to the high voltage battery when requested.
This is not serviceable part. It is part of the Heat pump valve unit and is replaced with the unit.
Slanted Condenser:
Coolling fan:
Refrigerant piping:
11-port (!) coolant distribution manifold:
The heat pump adds a new module called the heat pump valve control module (HPVCM), this is necessary to control THREE electronic expansion valves (EEVs) that can precisely control refrigerant flow. Also added are two cyclonic liquid gas separator valves, and a large suction accumulator. All this ensures the system can run efficiently and without liquid slugging the compressor through a wide range of operating conditions. A water cooled condenser has also been added, this is what will allow heat transfer from refrigerant to coolant for heating the cabin and battery. The new heat pump valve module, water cooled condenser, and accumulator has been located on the right side engine bay next to the A/C compressor. The battery coolant chiller that was previously in this location was moved on top of the cooling module air dam.
The 5 kW PTC heater is still present in the loop, this is a good thing because it means heat can be obtained from both the heat pump and the resistive heater. At low ambient conditions, the resistive PTC heater will take over since the heat pump output will be diminished. Unfortunately there is no information about the minimum operating temperature of the heat pump.
The design of the HVAC module behind the dash seems mostly unchanged. Liquid heater core and refrigerant evaporator like before. The only new mention I see is the ability to shut off the passenger footwell air vent when a passenger is not detected.
The cooling piping system has been repacked, but still maintains the same dual 5-way valve setup and 4x coolant pumps (one less on non-GTs) as the previous model year. (See this article for more information on the operation of the 5-way valves.) In theory, the system should allow heat transfer to and from pretty much any component in the system.
Service information (note, there are some errors):
Overall coolant and refrigerant piping diagram:
1 | Motor electronics coolant pump GT |
2 | Coolant temperature and pressure sensor |
3 | Auxiliary electric coolant pump |
4 | ISC |
5 | Rear electric drive assembly |
6 | Rear electric drive assembly oil cooler |
7 | High voltage battery |
8 | Cooling fan motor and shroud |
9 | High voltage battery coolant pump |
10 | Motor electronics coolant pump |
11 | Battery coolant diverter valve |
12 | Coolant distribution manifold |
13 | Front electric drive assembly oil cooler |
14 | Secondary ISC |
15 | High voltage battery power heater |
16 | Heater core |
17 | Degas bottle |
18 | High voltage battery coolant cooler |
19 | Radiator |
Heat pump assembly
1 | Heat pump valve unit |
2 | Heat pump valve control module (HPVCM) |
3 | Water cooled condenser (WCC) |
4 | Heat pump valve unit to evaporator line |
Heat pump valves
1 | Refrigerant pressure and temperature sensor a |
2 | Vapor injection heat pump heating electronic expansion valve (HEXV) |
3 | Vapor injection heat pump battery chiller electronic expansion valve (BCEXV) |
4 | Vapor injection heat pump cooling electronic expansion valve (CEXV) |
5 | Vapor injection heat pump cooling liquid gas seperator (CLGS) |
6 | Vapor injection heat pump heating liquid gas seperator (HLGS) |
Heat Pump Architecture
1 | Condenser |
2 | High voltage battery coolant cooler |
3 | Heat pump assembly |
4 | Refrigerant compressor |
5 | Refrigerant compressor bracket |
6 | Cabin coolant heater |
7 | Accumulator |
8 | Condenser inlet line |
9 | Refrigerant pressure and temperature sensor c |
10 | High voltage battery coolant cooler liquid line |
11 | Refrigerant vapor injection line |
12 | Refrigerant compressor outlet line |
13 | Evaporator inlet line |
14 | Refrigerant compressor to accumulator line |
15 | Evaporator outlet line |
16 | Thermostatic expansion valve |
17 | Condenser outlet line |
Vapor Injection Heat Pump (VIHP) System 8 Modes of Refrigerant Operation
The vapor injection heat pump (VIHP) system is a refrigerant system that provides both cooling and heating as needed throughout the vehicle using a heat pump valve unit that has a series of valves to control the temperature, pressure and direct the refrigerant flow according to the operation mode. The VIHP system provides cabin cooling by using the refrigerant cycle with a condenser (outside heat exchanger OHX) and an evaporator inside the HVAC climate control housing.
For cabin heating, the condenser (outside heat exchanger OHX) operation acts as an evaporator to absorb heat from the air, and the refrigerant to coolant water cooled condenser (WCC) is used to transfer heat from the refrigerant to the coolant. The coolant then passes through the heater core inside the HVAC climate control housing. A cabin coolant heater is also used to warm the coolant and provide heat to the cabin when requested.
Correct operation of the vapor injection heat pump (VIHP) system is highly dependent on the proper amount of refrigerant oil and refrigerant that is in the system.
Below are the 8 modes of the refrigerant system operation and the component that are used to achieve each of the 8 modes.
NOTE: The following diagrams show the refrigerant system state in each component.
(Cabin Cooling)
When cabin cooling is requested, the ACCM engages the refrigerant compressor and pumps refrigerant through the Water-Cooled Condenser (WCC) to the fully open vehicle injection heat pump heating expansion valve (HEXV), bypassing the heating liquid gas separator (HLGS) valve. The pressure and temperatures are measured by a pressure and temperature sensor "A", reporting to the PCM and vehicle injection heat pump compressor outlet temperature sensor, reporting to the HPVCM . These pressure and temperatures values are networked to the SOBDMC.
The refrigerant is routed to the condenser (aka the outside heat exchanger). The refrigerant condenses from a high pressure, high temperature gas to a high-pressure lower temperature liquid as it passes through the condenser.
The vapor injection heat pump low side refrigerant shut off valve (SOV) is closed as is the vapor injection heat pump battery chiller expansion valve (BCEXV) and the vapor injection heat pump cooling expansion valve (CEXV) opening percentage is controlled by monitoring the vapor injection heat pump outside heat exchanger outlet temperature. The vapor injection heat pump outside heat exchanger outlet temperature reports the refrigerant line temperature to the HPVCM . The HPVCM send a network message to the SOBDMC.
The refrigerant is routed through the vapor injection heat pump cooling liquid gas separator (CLGS) valve. To provide improved performance (typically above ambient temperatures of 68 °F/ 20°C) the CLGS opens to separate the high-pressure vapor/liquid refrigerant and provides vapor injection to the refrigerant compressor. The liquid refrigerant out of the CLGS continues to the evaporator on to the accumulator and back to the refrigerant compressor, in a closed refrigerant loop. The refrigerant temperature are measured by the vapor injection heat pump evaporator outlet temperature sensor, reporting to the HPVCM and network messaged to SOBDMC.
(Cabin Cooling and Battery Cooling)
When cabin cooling and battery cooling are requested, the operation for the cabin cooling operation remains the same as in cabin cooling. What is added to the system is cooling for the battery. The battery expansion valve (BEXV) is controlled by the high voltage battery coolant cooler outlet refrigerant superheat temperature that is determined by the refrigerant pressure and temperature sensor C that is reporting those values to the SOBDMC.
The refrigerant flows through the high voltage battery coolant cooler, which transfers cooling from the refrigerant to the vehicles coolant. The LIN controlled water pump is commanded on along with the 5 port valve is commanded to open the batter cooling system port, circulating the coolant through the high voltage battery cooling plate.
(Battery Cooling)
When battery cooling is requested without cabin cooling, the operation for the battery cooling operation remains the same as in cabin cooling and battery cooling , without cabin cooling portion of operation. The difference is the vapor injection heat pump cooling expansion valve (CEXV) and the vapor injection heat pump low side refrigerant shut off valve (SOV) are commanded to the off position, blocking refrigerant from entering the evaporator. The refrigerant is also routed to the TXV with shut off valve (SOV) to the high voltage battery coolant cooler that has a auxiliary chiller that transfers cooling to the coolant of the high voltage battery. The the 5 port valve is commands 100% of the coolant through the high voltage battery coolant cooler to the high voltage battery cooling plate, cooling the high voltage battery.
(Cabin Reheat)
When cabin reheat for ambient temperature greater than 68 degrees, occurs when the cooling load is high while the reheat load is relatively low. The electric water pump for the coolant heating circuit circulates coolant through the water cooled condenser (WCC) and then on through the activated high voltage cabin coolant heater. The coolant is routed through the heater core, raising the cabin temperature. The 5 port valve routes the coolant back to the electric coolant pump completing the coolant loop.
If the battery temperature is low, the 5 port valve can divert coolant through the coolant reservoir and the LIN controlled electric battery coolant pump flows coolant to the high voltage battery cooling plate to warm the battery arrays in the high voltage battery. Based on battery temperatures the 5 port valve regulates the coolant flow to control the high voltage battery temperatures.
The refrigerant from the refrigerant compressor passes through the water cooled condenser (WCC), vapor injection heat pump heating electronic expansion valve (HEXV), vapor injection heat pump heating liquid gas separator (HLGS) valve and directly on to the condenser (outside heat exchanger (OHX). The water cooled condenser (WCC) and condenser (outside heat exchanger (OHX) function as a condenser with refrigerant exiting as a high-pressure liquid.
The vapor injection heat pump low side refrigerant shut off valve (SOV) is closed and the liquid refrigerant is routed to the vapor injection heat pump cooling liquid gas separator (CLGS) valve. The percentage of the CLGS opening, controls the condenser (outside heat exchanger (OHX) temperature (subcooling) to meet the evaporator temperature sensor temperature target. Both the HLGS and the CLGS remain fully open in reheat mode and there is no vapor injection.
(Cabin Dehumidification )
The cabin dehumidification - 32°F to 68°F (0°C to 20°C) occurs when the cooling load is relatively low, while the reheat load is relatively high. During this mode the vapor injection heat pump system maintains the set temperature and regulates the cabin temperature by controlling the vapor injection heat pump cooling liquid gas separator (CLGS) valve for the condenser (outside heat exchanger (OHX) (with a lower limit to fully open) as well as the vapor injection heat pump heating electronic expansion valve (HEXV) for the water cooled condenser (WCC) outlet temperature. The refrigerant that enters the evaporator removes the moisture form the air passing over the fins to provide cabin dehumidification. Just like cabin reheat, vapor injection is not enabled in the dehumidification mode and both the CLGS and HLGS are fully open to allow free flow of the refrigerant.
The coolant circuit gains heat by passing through the WCC and the high voltage cabin coolant heater is activated if needed to provide additional heat to the coolant. The refrigerant compressor is engaged and the refrigerant exits the compressor and passes through the WCC. The refrigerant condenses and provides some heat to the coolant circuit.
The refrigerant leaves the WCC and passes through the HEXV, this is controlled for sub cool out of the WCC, then onto the condenser (outside heat exchanger (OHX). The condenser functions as an evaporator, absorbing heat from the ambient air.
(Cabin Heating)
When the system is operating in cabin heating mode, the operation is the same as cabin reheating mode 4. The LIN controlled electric water pump for coolant heating circuit circulates coolant through the water cooled condenser (WCC) and then through the activated high voltage cabin coolant heater. The heated coolant flows though the heater core to raise the cabin temperature. The 5 port valve routes the coolant back to the electric water pump to complete the heating loop.
If the battery temperature is low, the 5 port valve is controlled to open a coolant loop through the coolant reservoir and is circulated by the LIN battery coolant pump motor. The coolant flows though the battery cooling plate (in this instance heating plate) to warm the cell arrays in the high voltage battery. The high voltage battery temperature is monitored and the 5 port valve is controlled to regulate coolant flow controlling the battery temperature.
The refrigerant cycles from the refrigerant compressor through the vapor injection heat pump heating liquid gas separator (HLGS) valve , to the condenser (outside heat exchanger (OHX), through the vapor injection heat pump low side refrigerant shut off valve (SOV) and back to the accumulator before completing the refrigerant loop back at the refrigerant compressor as it does during thee deicing mode. The system uses pressure and temperature sensor inputs from the pressure and temperature sensor C, pressure and temperature sensor A, vapor injection heat pump compressor outlet temperature sensor and vapor injection heat exchanger outlet temperature sensor.
(Cabin Heating Plus Battery Cooling)
The operation for cabin heating plus battery cooling is the same as cabin heating mode 6, with the exception to the 5 port high voltage battery diverter valve shutting off heated coolant going to the high voltage battery cooling plate.
The LIN controlled electric water pump for coolant heating circuit circulates coolant through the water cooled condenser (WCC) and then through the activated high voltage cabin coolant heater. The heated coolant flows through the heater core to raise the cabin temperature. The 5 port valve routes the coolant back to the electric water pump to complete the heating loop.
If the battery temperature is high, the 5 port high voltage battery diverter valve is controlled to block the coolant from entering the high voltage battery coolant loop. The vapor injection heat pump battery chiller electronic expansion valve (BCEXV) opens in the refrigerant loop with the compressor circulating refrigerant to the high voltage battery coolant cooler. The chilled battery coolant is circulated by the LIN controlled electronic high voltage battery coolant pump through the high voltage battery cooling plate to cool the cell arrays in the high voltage battery.
(Deicing)
If the condenser (outside heat exchanger (OHX) externally freezes from the moisture in the air and ices up, the vehicle injection heat pump heating expansion valve (HEXV) opens up partially to allow refrigerant to warm the condenser (OHX) to defrost it. The vapor injection heat pump cooling expansion valve (CEXV) and vapor injection heat pump battery chiller electronic expansion valve (BCEXV) close during deicing and allows time for heat to be absorbed into the condenser (OHX). The active grill shutters remain closed with the cooling fan turned off during deicing mode. This prevents airflow from further cooling the condenser (OHX). The hot gas cycle allows the refrigerant to cycle tin a closed loop from the heat pump valve unit, to the condenser (OHX), through the open vapor injection heat pump low side refrigerant shut off valve (SOV), to the accumulator and then back to the refrigerant compressor. The pressure and temperature sensors are used to monitor the refrigerant during this refrigerant cycle.
Driver Focus Mode Feature ( if equipped)
The driver focus mode feature shuts off the air flow to the front passenger floor duct (footwell) when it is determined that front passenger seat is not occupied by utilizing front passenger occupancy seat sensor. When activated though the center display screen (touchscreen) the HVAC systems receives a network message that the front passenger seat occupancy seat sensor and then the front passenger footwell vent door actuator closes forcing fresh warm or cold air to focus the driver area demanding temperature cabin comfort.
Accumulator
The suction accumulator is designed to remove moisture from the refrigerant and to prevent any liquid refrigerant that may not have been vaporized in the evaporator core from reaching the refrigerant compressor. The refrigerant compressor is designed to pump refrigerant vapor only, as liquid refrigerant does not compress and can damage the refrigerant compressor. The suction accumulator is designed to remove moisture from the refrigerant and to prevent any liquid refrigerant that may not have been vaporized in the evaporator core from reaching the refrigerant compressor. The refrigerant compressor is designed to pump refrigerant vapor only, as liquid refrigerant does not compress and can damage the refrigerant compressor.
Heat Pump Valve Control Module
The HPVCM controls the operation of the vapor injection heat pump system. It uses inputs from other modules such as the HVAC control module, PCM and SOBDMC, to determine the percentage to open the expansion valves. It also communicates information, such as the heat pump mode, to other modules in the vehicle.
Heat Pump Valve Unit
The heat pump valve unit is comprised of various heat pump components that distributes refrigerant to the heat pump system. The heat pump valve unit consists of the following components.
- vapor injection heat pump heating liquid gas separator (HGLS) valve
- vapor injection heat pump cooling liquid gas separator (CLGS) valve
- vapor injection heat pump cooling electronic expansion valve (CEXV)
- vapor injection heat pump heating electronic expansion valve (HEXV)
- vapor injection heat pump battery chiller electronic expansion valve (BCEXV)
- vapor injection heat pump low side refrigerant shut off valve
- pressure and temperature sensor A
- water cooled condenser (WCC)
High Voltage Battery Coolant Diverter Valve
The high voltage battery coolant diverter valve is a 5 port valve that controls coolant flow in the high voltage battery and cabin heater loops. The heater loop can be isolated from the battery circuit to provide max cabin heater performance, or the loops can be combined in series to provide battery heating.
These components are in the cabin heater loop.
- cabin heater coolant pump
- cabin coolant heater
- heater core
- water cooled condenser (WCC)
- 5 port valve (proportional control for the battery coolant)
The vehicle is equipped with a refrigerant electric compressor and an ACCM , which are integral to each other. They cannot be removed or serviced separately. The ACCM has both low voltage and high voltage connections. The ACCM requires a 12 volt low voltage system operating voltage between 9 and 16 volts. The ACCM also requires high voltage system range between 110 and 422 volts. When the ACCM receives the A/C request message, it engages the refrigerant electric compressor. The refrigerant compressor purpose is to compress a low-pressure gas refrigerant to a high pressure, high temperature gas, creating a vapor compression cycle. The refrigerant compressor has the traditional suction and discharge ports. It has an additional third port for vapor injection allowing for a vapor injection cycle. A vapor injection cycle is an enhanced vapor compression cycle with a mid-pressure injection port which allows higher refrigerant mass flows. This increases efficiency through the full operating range and allows the heat pump to operate over a wider range of ambient temperatures compared to a normal heat pump. Instead of cycling ON and OFF like a traditional compressor, the refrigerant compressor speeds up or slows down as required and the compressor may run when the climate control is off to provide cooling to the battery. For the appropriate refrigerant and refrigerant oil, REFER Specifications.
Refrigerant Pressure and Temperature Sensor A
The Pressure and Temperature Sensor A monitors the pressure and temperature of the refrigerant as it is routed from the water-cooled condenser. This is a combined sensor, and the probe sits directly in the refrigerant flow. The temperature and pressure readings are monitored by the PCM and SOBDMC . This pressure and temperature sensor is part of the heat pump valve unit and is not serviced separately from the unit.
Refrigerant Pressure and Temperature Sensor C
The Pressure and Temperature Sensor C monitors the pressure and temperature of the refrigerant as it is routed from the water-cooled condenser. This is a combined sensor, and the probe sits directly in the refrigerant flow. The temperature and pressure readings is monitored by the SOBDMC . If this pressure and temperature sensor is being replaced, it should not be removed unless the refrigerant system has been successfully evacuated.
Vapor Injection Heat Pump Battery Chiller Electronic Expansion Valve (BCEXV)
When commanded by the HPVCM , the electronically controlled Battery Chiller Electronic Expansion Valve (BEXV) decreases the refrigerant pressure downstream of the BEXV. This allows refrigerant to flow to the high voltage battery coolant cooler to cool the high voltage battery.
This is not serviceable part. It is part of the Heat pump valve unit and is replaced with the unit.
Vapor Injection Heat Pump Cooling Electronic Expansion Valve (CEXV)
The CEXV is an electronically controlled expansion valve. When commanded by the HPVCM , the refrigerant pressure is decreased downstream of the CEXV. The CEXV can be commanded fully open to allow refrigerant to pass without changing the pressure.
This is not serviceable part. It is part of the Heat pump valve unit and is replaced with the unit.
Vapor Injection Heat Pump Heating Electronic Expansion Valve (HEXV)
The HEXV is an electronically controlled expansion valve. When commanded by the HPVCM , the HEXV starts to close from the fully open position so that the refrigerant pressure upstream of the HEXV increases. The increase in pressure, increases the temperature of the refrigerant as well, because the coolant is at a lower temperature than the refrigerant, heat transfer from the water cooled cooler WCC to the coolant occurs. If not activated, the HEXV stays fully open to allow the refrigerant to pass without changing the refrigerant pressure.
This is not serviceable part. It is part of the Heat pump valve unit and is replaced with the unit.
Vapor Injection Heat Pump Cooling Liquid Gas Separator (CLGS) Valve
The Cooling Liquid Gas Separator (CLGS) valve operates in the same way as the heating liquid gas separator (HLGS) valve. It separates vapor refrigerant and feeds it back to the vapor injection port on the refrigerant compressor. Liquid refrigerant exits the CLGS and goes to the internal evaporator where it changes state from a low-pressure liquid to a low-pressure gas, absorbing heat and providing cool air to the cabin.
This is not serviceable part. It is part of the Heat pump valve unit and is replaced with the unit.
Vapor Injection Heat Pump Heating Liquid Gas Separator (HLGS) Valve
Liquid Gas separators are required to achieve vapor injection. Two phase (liquid and vapor) refrigerant enters the HLGS from the heating electronic expansion valve. The internal design of the liquid gas separator creates a cyclone which separates vapor refrigerant from liquid. The vapor is then routed back to the vapor injection port on the refrigerant compressor. At the same time, the two-phase refrigerant exits the HLGS and passes on to the condenser (Outside Heat Exchanger (OHX)) where it evaporates and absorbs heat from the environment.
This is not serviceable part. It is part of the Heat pump valve unit and is replaced with the unit.
Vapor Injection Heat Pump Compressor Outlet Temperature Sensor
This is a temperature sensor that is affixed to the refrigerant line. I measures the temperature of the refrigerant coming out of the refrigerant compressor.
Part of the refrigerant line Not serviceable part.
Vapor Injection Heat Pump Evaporator Outlet Temperature Sensor
This is a temperature sensor that is affixed to the refrigerant line. I measures the temperature of the refrigerant coming out of the evaporator.
Part of the refrigerant line Not serviceable part.
Vapor Injection Heat Pump Outside Heat Exchanger Outlet Temperature Sensor
This is a temperature sensor that is affixed to the refrigerant line. It measures the temperature of the refrigerant coming out of the condenser (outside heat exchanger (OHX)).
Part of the refrigerant line Not serviceable part.
Vapor Injection Heat Pump Low Side Refrigerant Shut Off Valve
This is a simple solenoid valve that is used to allow flow from the outside heat exchanger to the accumulator, bypassing the evaporator and chiller circuit when the heat pump is operating in heating or de-icing modes. In all other modes it remains closed.
This is not serviceable part. It is part of the Heat pump valve unit and is replaced with the unit.
Water Cooled Condenser (WCC)
The water cooled condenser (WCC) is a heat exchanger. It works by cooling down the refrigerant by removing the heat from the refrigerant vapor and transferring it to the coolant that is routed through the WCC. The coolant is fed to the heater core inside the HVAC case to provide heat to the cabin and to the high voltage battery when requested.
This is not serviceable part. It is part of the Heat pump valve unit and is replaced with the unit.
Slanted Condenser:
Coolling fan:
Refrigerant piping:
11-port (!) coolant distribution manifold:
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