Is it normal for the E-heat to come on with the AC?

[BMT1071]

But then that means my arms and face are nice and chilled while my feet and shins sweat. ?

The systems follow general hot air rises/cold air sinks principles when in auto mode.
Can you provide a link/page number to where you got the information that e-heat is radiant from the floor? This is the first I have heard of that.

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[timbop]

...
Although, the manual also says it switches on by default.
...

Based on that manual page and common sense, the "eheat" button simply enables the resistive heating element which only actually comes on IF THE TEMPERATURE IS BELOW the set temperature in the climate control system. In the winter the A/C button is also often enabled, but if does not kick on if it is freezing cold. I personally believe both are really "cancel" switches if NOT enabled. That is, it won't turn on the resistive element no matter how cold the cabin is if it is not ENABLED.

This thread is purely speculation so perhaps an actual Ford engineer that knows can speak up to clarify

 

[noway]

This answer is slightly longer than necessary, but I have to explain a few things for this to make sense I think..

The thermal loop in this case is one loop containing the HVB, the "E heater", a refrigerant cooler connected to the AC system, and the heater for the cabin. This loop can be divided into two loops fully or partially where the coolant only goes through the E-heater and the cabin heater.

The purpose of this loop is to cool the battery, heat the battery and to heat the cabin (note: cooling the cabin is not included). To do this it will select between several modes of how the coolant loop is used.

Components in this loop:
- The heater core for the cabin, just like a regular car heater element. Water is being circulated through it to heat the air for the cabin.
- The high voltage battery cooler. This cooler is connected to the air conditioner coolant loop and is used to directly cool the coolant (water) from the air conditioning refrigerant.
- The "E-heater". This is a 5kW electric heater element used to "boil" the coolant. It will either be used to heat the battery and the cabin heater element, or just to heat the cabin element (note: It cannot just heat the battery coolant). This heater is not on/off, it has variable power depending on what is necessary.
- Two electric pumps and two valves to divide the circuits to allow heating just the cabin or to circulate the coolant through all components (not just on/off, it can be varied).

So slightly towards and actual answer on the question:

This thermal loop can be in one (or partially) in these modes:
- Heating the cabin. E-heater is on and heating water circulating between heater core (cabin heater) and the e-heater element. Water is circulated thorugh the HVB, but loops are fully or partially disconnected.
- Heating the battery AND the cabin air. Both pumps are running and valves are opened to allow coolant to flow through all the components to heat the battery and to heat the cabin air. Battery heating can be prioritized by reducing air flow in cabin heater.
- Cooling the battery using the cabin as heat receiver. If possible and when battery needs cooling, but cabin air can receive the heat from the battery it can have the E-heater off (or reduced), circulate the coolant thorugh the HVB and the heater core to transfer heat from battery to cabin.
- Cooling the battery using the air conditioning compressor/system. The coolant is circulated through the HVB and the refrigerant cooler. In this mode the air conditioning system will be used to remove heat from the battery by cooling the coolant directly. This is necessary if ambient temperature is too hot and battery needs to be at a lower temperature than ambient air, or if more cooling is necessary than previous step can provide.

To allow the HVB to be kept at the right temperature the system will override the selection on E-heater on/off or AC on/off on the screen and will turn those on even when disabled if necessary for the battery thermal management.

Since the air conditioning evaporator is placed before the cabin heater core (in the air flow) it will also technically be possible to cool the battery by using the heater core in combination with air conditioning. The evaporator will heat incoming air (and remove some moisture at the same time) and heater core will add heat to the air afterwards by cooling the coolant which will flow through the heater core and then through the HVB.

There is no radiator in this coolant loop other than the cabin heater core, so for cooling the battery it either has to use the cabin as heat receiver or it has to use the air conditioning system. It cannot air cool the battery coolant directly.

There is an aditional cooling loop with no connection to the first which circulates through the motors, electronics and a radiator at the front.

Also, using air conditioning in combination with heating is the normal way for automatic climate control in ICE vehicles to work. It cannot vary the temperature on the evaporator so it will have to blend heat into the cooled air to get the correct temperature, and at the same time providing some cooling for the engine.

There are several variants of thermal management of electric vehicles, so for example:
- Tesla uses one loop which can be divided into several loops by valves and pumps. It can move heat from the motors into the battery or the cabin. As far as I know. before heat pump it actually uses the motors as heating elements (running DC into the motor when stationary will just use the windings as a heater). This replaces the dedicated heating element.
- The Nissan Leaf has no coolant in the batteries. It has a heating element inside the battery (not in all models in all areas) to provide heat.
- The Chevy Bolt has three coolant loops. The cabin heater and electric heater is its own loop separated from the HVB circuit.
- Some Hyundais uses cabin air to cool the battery by drawing heat under the back seats from the cabin (which is air conditioned already) and uses this to cool the batteries directly.

 

[theo1000]

God! there is a lot of bad information in this thread.

The only accurate post is the one Mach-lee posted. Folks please reread that post before posting more inaccurate speculation.

 

[prdude]

God! there is a lot of bad information in this thread.

The only accurate post is the one Mach-lee posted. Folks please reread that post before posting more inaccurate speculation.

the post from noway is also quite accurate

 

[jojomontag]

So E-heat works just like the heater core in a regular car. There is a heating element that heats coolant, and that coolant passes through a radiator in the HVAC box that heats the air going through it. The warm air can be directed anywhere from the defrost vents, floor, to the panel depending on settings, again just like a regular car. It's not a radiant heater in the floor.

If you use recirc, then it's going to run the heat to dehumidify the air unless you turn it off, otherwise it would get very stuffy inside the cabin as the humidity from your breath and skin builds up. Because the A/C is so efficient, it doesn't get cold enough to dehumidify effectively without overcooling the cabin, so this is why a little bit of heat is needed so the A/C evap temp can be dropped down into a dehumidifying range without you freezing to death from lack of reheat. The settings default to more of a comfort strategy by default rather than an efficiency strategy, if you want max efficiency then you can shut things off.

It's not the engineers' fault that the service techs haven't done their training and aren't up to par. Blame management then. I can take a look at your codes if you want another opinion.

I'm just having a hard time reconciling the idea, especially when it affects the efficiency so much, but I just try to keep learning. It'll make sense at some point. Would be nice if such things were included in the manual, though, because if it is as you say, it sounds like messing with it could be problematic rather than just letting the car do what it is programmed to do automatically.

I attached the OBDII DTC scan. I checked myself since the service advisor wouldn't tell me any more than what my FordPass app tells me. One DTC (an isolation fault) set off the light, but there are several others, including a few that indicate that communication was lost with modules.

 

[jojomontag]

The systems follow general hot air rises/cold air sinks principles when in auto mode.
Can you provide a link/page number to where you got the information that e-heat is radiant from the floor? This is the first I have heard of that.

I read it somewhere a few months ago, but I just cannot find it now. If I do, I'll share it.

 

[theo1000]

the post from noway is also quite accurate

Unfortunately no.

Read it again WRT e-heat. It is wildly inaccurate speculation. Read the below again. Does this mean this is how the Mach-E E-Heat is set up? Does not sound like he knows but is still speculating. I'm not even sure he is talking about the Mach-E. Very confusing.

He seems to be claiming the E-Heat is for battery thermal management and I'm not sure we have that sort of control over it. The E-heat is only for the cabin. To prevent recirculated A/C air from becoming too cold as Mach-Lee noted.

This answer is slightly longer than necessary, but I have to explain a few things for this to make sense I think..

The thermal loop in this case is one loop containing the HVB, the "E heater", a refrigerant cooler connected to the AC system, and the heater for the cabin. This loop can be divided into two loops fully or partially where the coolant only goes through the E-heater and the cabin heater.

The purpose of this loop is to cool the battery, heat the battery and to heat the cabin (note: cooling the cabin is not included). To do this it will select between several modes of how the coolant loop is used....

...
To allow the HVB to be kept at the right temperature the system will override the selection on E-heater on/off or AC on/off on the screen and will turn those on even when disabled if necessary for the battery thermal management.

Since the air conditioning evaporator is placed before the cabin heater core (in the air flow) it will also technically be possible to cool the battery by using the heater core in combination with air conditioning. The evaporator will heat incoming air (and remove some moisture at the same time) and heater core will add heat to the air afterwards by cooling the coolant which will flow through the heater core and then through the HVB....

 

[BMT1071]

Unfortunately no.

Read it again WRT e-heat. It is wildly inaccurate speculation.

So you have more accurate info from Ford that you can share?

 

[jojomontag]

So you have more accurate info from Ford that you can share?

Only info from Ford directly would not be speculative. Even the teardowns by Munro are speculative. He shows us how it is all put together, but even he scratches his head and speculates why Ford decided to do things a certain way.

 

[noway]

My information is from the Ford service workshop manual (from Ford directly.. just to clarify), I wish I could share it as-is, but not sure about copyright laws. if that manual is not correct then probably nothing is correct. In europe, at least, this manual is publicly available for purchase/view online on Ford Etis (partially by EU requirement)

 

[prdude]

Unfortunately no.

Read it again WRT e-heat. It is wildly inaccurate speculation. Read the below again. Does this mean this is how the Mach-E E-Heat is set up? Does not sound like he knows but is still speculating. I'm not even sure he is talking about the Mach-E. Very confusing.

He seems to be claiming the E-Heat is for battery thermal management and I'm not sure we have that sort of control over it. The E-heat is only for the cabin. To prevent recirculated A/C air from becoming too cold as Mach-Lee noted.

I believe what noway means to say is that the electric heater or PTC heater that heats the coolant to flow through the heater core can also feed that heated coolant to the HVB. This is indeed accurate, as can be seen be following the jumble of heater hoses underhood.

 

[theo1000]

I believe what noway means to say is that the electric heater or PTC heater that heats the coolant to flow through the heater core can also feed that heated coolant to the HVB. This is indeed accurate, as can be seen be following the jumble of heater hoses underhood.

But that says nothing about the E-Heat button we can turn off or turn on. Can does not mean 'will'. That is the only thing I'm interested in. What does the E-Heat button do?

 

[noway]

To clearify this, my point is that there are two systems, one being battery management, the other being cabin hvac, both sharing the AC compressor and the PTC element, the screen only selects what the HVAC system MAY use, the battery management overrides this.

There is ONE PTC heater element in the Mach-E. The E-heat button on the screen controls if it is used for cabin heating or not. It is not "the E-heater", E-heat is just a software thing on the screen, and enables the use of the PTC element for cabin heating.

The thermal management system is either in heating mode or in cooling mode. In heating mode it will switch between two modes:
1: Cabin heat is required quickly (requires the full 5kW power of the heater). Coolant will only flow through the cabin heater core and PTC element. HVB being its own circuit, no heater in this circuit so no active battery heating.
2: Battery needs heating, cabin needs heating, but cabin does not require full 5kW power: The circuits are merged into one, coolant is flowing through the cabin heater core, the PTC element and HVB, heating both by using the single PTC element.

if battery cooling is requred, there are two phases (from manual)
1: Cooling phase 1 (Fords term from manual). Cabin needs heat, battery needs cooling. The PTC element is turned off and coolant is flowing through the cabin heater core, the disabled PTC element, and HVB, effectively cooling the battery by heating the cabin.
2: Cooling phase 2 (when cabin can't take enough heat, or outside air temperature is too high): An additional valve is being opened to allow coolant to be cooled by the AC system using an additional evaporator in the AC refrigerant circuit (water to refrigerant cooler). In this case the AC compressor is running, regardless of setting on screen, this also applies when charging when car is turned off.

The confusion here is about the E-heat and A/C settings on the HVAC screen, which controls IF the system can use/turn on those based on requirement. It does not mean it is on, and both are not on/off, they can be regulated. Heater can be in several power modes, the AC compressor has variable speed. I have seen with outside temperature of 30C/78F that the whole car consumes about 800-900W of power parked for hours with A/C running for cabin cooling.

This is how the circuit looks like:

           <==================================================================<
          ||                                                                  ||
          ||                           |-----------|                          ||
          ||                     >====>|  Exp tank |==========================||
          ||                    ||     |-----------|                          ||
          ||                    ||                                            ||
          ||                    ||   -----------------                        ||
          ||   |----------|     ||   |                |                |----------------|
          ||   |    HVB   |>========>| diverter valve |>==============>| Refrig. cooler |
          ||   |----------|          |                |                |----------------|
          ||        ^^               ------------------
          ||        ||                         vv
          ||    |--------|                     ||
          ||    |  pump  |                     ||
          ||    |--------|                     ||
          ||        ^^                         ||
          ||        ||                         vv
          ||        ||                   |-------------|
          ||        ||                   |             |         |--------|
          |>=======>||===================| 4 way valve |>=======>|> Pump >|>=====>
                    ||                   |             |         |--------|      ||
                    ||          ||======>|             |                         ||
                    ||          ||       --------------|                         ||
                    ||          ||                                               ||
                    ||          ||                                               ||
                    ||          ||     |-------------------|   |-------------|   ||
                    ||<===============<| Cabin heater core |<=<| PTC heater  |<==<
                                       |-------------------|   |-------------|

 

[BMT1071]

But that says nothing about the E-Heat button we can turn off or turn on. Can does not mean 'will'. That is the only thing I'm interested in. What does the E-Heat button do?

Great that that is your question, but why throw shade on @noway?? His post sure looked like it was, and has been since confirmed to be, right out of the MME shop manual. The forum member you mention as being the only one worth reading has on more than one occasion authoritatively posted things that are demonstrably false.
I had to use the 'show ignored content' button to see that post.

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