Heater not working.

[Lord Polymath]

I did the same test when temp was only cool outside, let's say 50F and could barely get any heat even with the E-Heat turned on. But now we are starting to get colder, 32F, E-Heat is very efficient and heat up the cabin real fast. It SEEMS that if the car does not sense cold temp outside, even with E-Heat on, you will not get much heating.

I'd say wait until it gets real cold outside to test it before taking it in to the dealer.

That makes sense. It's probably a software adjustment that needs to be made.

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[generaltso]

It SEEMS that if the car does not sense cold temp outside, even with E-Heat on, you will not get much heating.

Correct. That's how a PTC heater works. It would be very inefficient to produce more heat than it needs.

 

[breeves002]

Correct. That's how a PTC heater works. It would be very inefficient to produce more heat than it needs.

It's also a safety thing. If you leak all of your coolant out the heater won't just melt everything around it trying to heat nothing.

When the cabin coolant pump failed on my FFE you'd see the heater come on full blast then after ~10 seconds it would suddenly just ramp down to nearly 0 as the element got up to temp.

 

[dtbaker61]

The MME doesn’t have a heat pump.

How sure are we about that?

I would have guessed that the compressor used for the A/C is reversible, and is basically like a household 'mini-split' which can handle both heating and cooling and IS a 'heat pump'.... All the sophisicated valves and pumps seem designed to scavenge heat when possible to move heat/cooling and move heat from battery environment to cabin when possible.

Typical heat pumps usually output 110-115 F degree hot, and 40-50 degree cold using the same compressor.... are we sure this is not what the MME is using?

The max defrost may have an additional resistive heater coil for max heat, but probably adds a 2kW load.

 

[generaltso]

How sure are we about that?

100%

 

[prdude]

100%

200%

 

[Badger_Prof]

For the record, I am perfectly happy with the heating for my Mach-E. I have driven it in temps from -19F to 94F. In the cold weather, I keep e-heat turned on and things work great. Yes, the range drops. In my first week temps ranged from a low of -19F to a high of +9F. I averaged 240 miles per charge with my ER AWD Premium with cabin temp set to 71 and both seat and steering wheel heat on. In September when temps were very moderate, I averaged 310 miles.

 

[David-HC]

I almost can’t believe the dealer and engineers would tell you to turn it off.

Just hit auto and adjust the temp. It will turn the PTC heater on as necessary. In Fords previous EVs there was no manual way to turn off the heater. The HVAC decided to turn it on and off automatically.

Hi Sam,

Thanks for this - really helpful ?

Just a quick question on the Auto setting! When I select auto, the climate screen display does not show or allow you to direct the heat to specific vents. If you click on say the dash-level vents, it seems to exit Auto mode ?

Or is this just me ........ ?

Cheers
David

 

[breeves002]

Hi Sam,

Thanks for this - really helpful ?

Just a quick question on the Auto setting! When I select auto, the climate screen display does not show or allow you to direct the heat to specific vents. If you click on say the dash-level vents, it seems to exit Auto mode ?

Or is this just me ........ ?

Cheers
David

This is correct. In auto mode it will not let you change modes. However if you do change the mode the e-heat will still come on/off automatically unless you manually press it on or off.

 

[Stang68]

Hi Sam,

Thanks for this - really helpful ?

Just a quick question on the Auto setting! When I select auto, the climate screen display does not show or allow you to direct the heat to specific vents. If you click on say the dash-level vents, it seems to exit Auto mode ?

Or is this just me ........ ?

Cheers
David

This is the same for any car (at least ones I've been in). When you use "Auto" it will blow out at the appropriate speed and vents it needs to reach that desired temperature by any means necessary. The nice thing about the Mach E is that you get three "Auto" levels so it doesn't blow at full blast if you don't want it to.

If you attempt to change the vent the air is coming out of, it will think you don't want auto anymore. Been like that on my Hyundai and Kia models, too.

 

[SnBGC]

There are basically two cooling circuits...Motor/Electronics and HVB/Cabin. The HVB/Cabin is a combo Heating or Cooling circuit where the battery and cabin heater have their own isolated loops that can be combined under certain conditions to share heat when available.

However, the Workshop Manual appears to have conflicting information. For instance:

Cabin Heat

The cabin coolant heater circuit provides warm coolant to the heater core to warm the passenger compartment. A PCM controlled cabin coolant heater warms the coolant. The cabin heater diverter valve allows warm coolant from the electric motor circuit, when available, to enter the cabin heater circuit to provide warm coolant for cabin heat. The upper temperature limit for the cabin heater circuit is 80°C (176°F). An ECT sensor in the cabin heater circuit provides the PCM with coolant temperature information

I believe there is an error in the above statement because the Electric Motor Circuit is separate and does not mix with the Cabin Heat/HVB circuit at any time. There isn't even a heat exchanger that I can see anywhere so I don't see how it is physically possible for the heat generated by the motors and electronics to warm the cabin at any time.

Later in the WSM is a more reasonable statement:

Cabin Coolant Heater

The cabin coolant heater has both low voltage and high voltage electrical connections. The low voltage circuits are used for controlling the unit, while the high voltage circuits are used for heating the coolant. The cabin coolant heater uses electricity, or more accurately, the heat for resistance in electrical circuits to quickly raise the temperature of the coolant to normal operating temperature. The SOBDMC sends power to the cabin coolant heater and controls the LIN circuit to the heater.


Cabin Heater Coolant Diverter Valve

The default state of the cabin heater coolant diverter valve is de-energized, placing the system into the isolated loop mode. Coolant flows out of the valve, then back, in the following order:

• cabin heater coolant pump
• cabin coolant heater
• cabin heater coolant temperature sensor
• heater core
• cabin heater coolant diverter valve

When energized by the PCM, the cabin heater coolant diverter valve places the system into the combined loop mode. Coolant flows out of the valve, then back, in the following order:

• cabin heater coolant pump
• cabin coolant heater
• cabin heater coolant temperature sensor
• heater core
• cabin heater coolant diverter valve
• HV battery coolant pump
• HV battery
• Traction battery coolant proportional valve
• cabin heater coolant diverter valve

What I would like to know is what happens when E-Heat is enabled or disabled? What happens REALLY? I originally thought it disables the PTC heater but now I think it might just force the system into isolated loop mode. When I have time I will try and find the PID for the cabin heater diverter valve and the cabin coolant heater and see what happens when I mess with the E-Heat button. I will have to wait until it gets pretty cold though because the PTC heater really needs cold coolant in order for the resistors to allow current to pass through it. I don't think much will happen at moderate temps but I could be mistaken. Will be interesting to see what happens.
Need cooler temps though.....

 

[dtbaker61]

There are basically two cooling circuits...Motor/Electronics and HVB/Cabin. The HVB/Cabin is a combo Heating or Cooling circuit where the battery and cabin heater have their own isolated loops that can be combined under certain conditions to share heat when available.

However, the Workshop Manual appears to have conflicting information. For instance:

Cabin Heat

The cabin coolant heater circuit provides warm coolant to the heater core to warm the passenger compartment. A PCM controlled cabin coolant heater warms the coolant. The cabin heater diverter valve allows warm coolant from the electric motor circuit, when available, to enter the cabin heater circuit to provide warm coolant for cabin heat. The upper temperature limit for the cabin heater circuit is 80°C (176°F). An ECT sensor in the cabin heater circuit provides the PCM with coolant temperature information

I believe there is an error in the above statement because the Electric Motor Circuit is separate and does not mix with the Cabin Heat/HVB circuit at any time. There isn't even a heat exchanger that I can see anywhere so I don't see how it is physically possible for the heat generated by the motors and electronics to warm the cabin at any time.

Later in the WSM is a more reasonable statement:

Cabin Coolant Heater

The cabin coolant heater has both low voltage and high voltage electrical connections. The low voltage circuits are used for controlling the unit, while the high voltage circuits are used for heating the coolant. The cabin coolant heater uses electricity, or more accurately, the heat for resistance in electrical circuits to quickly raise the temperature of the coolant to normal operating temperature. The SOBDMC sends power to the cabin coolant heater and controls the LIN circuit to the heater.


Cabin Heater Coolant Diverter Valve

The default state of the cabin heater coolant diverter valve is de-energized, placing the system into the isolated loop mode. Coolant flows out of the valve, then back, in the following order:

• cabin heater coolant pump
• cabin coolant heater
• cabin heater coolant temperature sensor
• heater core
• cabin heater coolant diverter valve

When energized by the PCM, the cabin heater coolant diverter valve places the system into the combined loop mode. Coolant flows out of the valve, then back, in the following order:

• cabin heater coolant pump
• cabin coolant heater
• cabin heater coolant temperature sensor
• heater core
• cabin heater coolant diverter valve
• HV battery coolant pump
• HV battery
• Traction battery coolant proportional valve
• cabin heater coolant diverter valve

What I would like to know is what happens when E-Heat is enabled or disabled? What happens REALLY? I originally thought it disables the PTC heater but now I think it might just force the system into isolated loop mode. When I have time I will try and find the PID for the cabin heater diverter valve and the cabin coolant heater and see what happens when I mess with the E-Heat button. I will have to wait until it gets pretty cold though because the PTC heater really needs cold coolant in order for the resistors to allow current to pass through it. I don't think much will happen at moderate temps but I could be mistaken. Will be interesting to see what happens.
Need cooler temps though.....

my guess is that it may be possible to extract some heat from battery/motor loops and dump it into the cabin as long as e-heat is off. i.e. set cabin temp to 85, e-heat off, and you MIGHT get more than 5 seconds of peak output before battery/inverter/motor temps throttle you back.

I used to have to turn defroster+heat on full blast at stoplights in the summer to prevent my '66 Tiger from overheating, The heater core pulled out just enough heat when motor radiator fan was at low rpm. I finally fixed with a big electric fan in front of radiator....

 

[JoeDimwit]

An internal combustion engine is going to be way better at producing heat than a heat pump.

The Mach-E does not have a heat pump.

 

[SnBGC]

my guess is that it may be possible to extract some heat from battery/motor loops and dump it into the cabin as long as e-heat is off. i.e. set cabin temp to 85, e-heat off, and you MIGHT get more than 5 seconds of peak output before battery/inverter/motor temps throttle you back.

I used to have to turn defroster+heat on full blast at stoplights in the summer to prevent my '66 Tiger from overheating, The heater core pulled out just enough heat when motor radiator fan was at low rpm. I finally fixed with a big electric fan in front of radiator....

Interesting enough.....the motors and electronics get much warmer than the HVB. Around 158F according to the WSM. But of course the mass is much less so that heat can be more effectively managed I think.

The radiator in front of the car only exchanges heat with the Motor/Electronics coolant loop. It doesn't get involved at all with the HVB/Cabin fluid circuit. The only time the fluid from the motor/electronics loop comes close to the fluid from the HVB/Cabin loop is at this hose assembly. To me it just looks like two hoses side by side with no valve or heat exchanger so the note in the WSM about sharing heat doesn't make sense to me.

The RWD, Base AWD and GTs each have different plumbing up front. This is the base AWD diagram...

 

[Bonehead]

It's also a safety thing. If you leak all of your coolant out the heater won't just melt everything around it trying to heat nothing.

When the cabin coolant pump failed on my FFE you'd see the heater come on full blast then after ~10 seconds it would suddenly just ramp down to nearly 0 as the element got up to temp.

Hi. I've had my MME for a week now, and the heater has come on suddenly full blast by itself 4 times. (I shut it down before waiting to see if it would ramp down on its own.) I also noticed a small puddle of what appeared to be water under the car in the garage. Is this what you're referring to?

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