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

[JoeDimwit]

Title says it all. It just seems like a waste of electricity to both heat and cool the air at the same time.

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[Motomax]

It’s a common way to reduce humidity and prevent Windows from fogging.

https://www.macheforum.com/site/thr...-windshield-anti-fogging-strategy-ewafs.8462/

 

[jojomontag]

Title says it all. It just seems like a waste of electricity to both heat and cool the air at the same time.

I have had the same issue, especially when selecting "Auto". Temp is set at 68° and it's hot outside, but the E-Heat comes on automatically, so I avoid auto. But sometimes, even though the car should be using the same settings as last time, I see that E-Heat has randomly turned on. It makes no sense.

 

[v8318cid]

The one downside I've found to the UI (aside from the periodic screen scramble I've mentioned here before) is the lack of a power usage meter. Sure the e-Heat button is active, but how much power it is drawing is an unknown. It is entirely possible that the system is active, but drawing a negligible amount of power at the time. Of course the opposite is also possible. Hey Ford, how 'bout adding a power usage meter at some point? Curious minds want to know!

On the note of heating and cooling at the same time, picture this - ever heard of the Bishop and Babcock system? Only way to prevent the A/C from running was to remove the belt from the compressor. Nevermind the inherent inefficiencies of this type of system (a/c in the trunk, heat in the dash/cowl; completely separate systems). A few great articles out there on this system, if you get into that sort of thing.

 

[theo1000]

I always turn it off. If I need to remove condensation I can always turn it on manually. Havn't seen any impact range wise either way.

 

[jojomontag]

The one downside I've found to the UI (aside from the periodic screen scramble I've mentioned here before) is the lack of a power usage meter. Sure the e-Heat button is active, but how much power it is drawing is an unknown. It is entirely possible that the system is active, but drawing a negligible amount of power at the time. Of course the opposite is also possible. Hey Ford, how 'bout adding a power usage meter at some point? Curious minds want to know!

On the note of heating and cooling at the same time, picture this - ever heard of the Bishop and Babcock system? Only way to prevent the A/C from running was to remove the belt from the compressor. Nevermind the inherent inefficiencies of this type of system (a/c in the trunk, heat in the dash/cowl; completely separate systems). A few great articles out there on this system, if you get into that sort of thing.

I usually know it is on because I monitor my efficiency--the car will drop from the usual 3.8-4.4 mile/kw to 2.7-3.1 mi/kw, so it is definitely drawing power.

My MME is currently in the shop for a service vehicle soon light (powertrain detected a fault in the high voltage system). I suspect some software/module issues since I can completely charge and still average excellent mileage, and I have not experienced any power loss. I wonder if this E-Heat issue is related.

 

[Brutakus]

I assumed when e-heat was checked, that it's only on when you use the heat?
It explains itself as a way to heat the cabin faster before the normal heater can kick in fully. That doesn't really sound to me like it would activate with A/C- just choosing in advance that you want faster heat when you turn on the heat.

 

[jojomontag]

It’s a common way to reduce humidity and prevent Windows from fogging.

https://www.macheforum.com/site/thr...-windshield-anti-fogging-strategy-ewafs.8462/

Sadly, I don't think this applies. The E-Heat only eminates heat through the floor and has no effect on the windshield. Although, I guess it could be to dry out humidity detected around anything in the floor/battery compartment. But, of course, Ford does not advertise this anywhere, not even in the manual (that I have seen--I obsessed over reading the manual).

 

[BMT1071]

Sadly, I don't think this applies. The E-Heat only eminates heat through the floor and has no effect on the windshield. Although, I guess it could be to dry out humidity detected around anything in the floor/battery compartment. But, of course, Ford does not advertise this anywhere, not even in the manual (that I have seen--I obsessed over reading the manual).

I have not seen a diagram of the HVAC case, but I'm fairly certain you can direct heated air to whichever vent you choose. In auto it will use the floor vents for heat and the panel vents for A/C.

 

[Raymondjram]

The one downside I've found to the UI (aside from the periodic screen scramble I've mentioned here before) is the lack of a power usage meter. Sure the e-Heat button is active, but how much power it is drawing is an unknown. It is entirely possible that the system is active, but drawing a negligible amount of power at the time. Of course the opposite is also possible. Hey Ford, how 'bout adding a power usage meter at some point? Curious minds want to know!

On the note of heating and cooling at the same time, picture this - ever heard of the Bishop and Babcock system? Only way to prevent the A/C from running was to remove the belt from the compressor. Nevermind the inherent inefficiencies of this type of system (a/c in the trunk, heat in the dash/cowl; completely separate systems). A few great articles out there on this system, if you get into that sort of thing.

Now you can just remove the fuse from the circuit that feeds the compressor. My Fusion Hybrid has no belts or pulleys on its engine, so this way also works on my car.

 

[Mach-Lee]

Sadly, I don't think this applies. The E-Heat only eminates heat through the floor and has no effect on the windshield. Although, I guess it could be to dry out humidity detected around anything in the floor/battery compartment. But, of course, Ford does not advertise this anywhere, not even in the manual (that I have seen--I obsessed over reading the manual).

The HVAC system does monitor the humidity level in the car, and if it gets too high it will change the strategy, which may include switching to a dehumidification mode where both the heat and A/C are run at the same time. I'd imagine if you let it run for 10 minutes the heat usage would eventually decrease as the humidity drops. If you live somewhere humid, it's probably normal to see both heat and A/C on.

You have to remember in a normal car the heater core is always hot with the engine and is used to warm the air up to the desired temp after the A/C core. On the Mach-E, the amount of heat and cooling can be adjusted independently, so it's possibly only a small amount of heat is being used. Either way probably not a big concern unless you are trying to push your range.

Try to get in the habit of leaving your set temp in the same place all the time in auto, typically 70-75ºF to minimize energy use. The car knows best, sometimes using recirc with heat will use less energy than full outside air with A/C only, especially if it's really hot out. I'd trust the Ford engineers on this one.

 

[jojomontag]

I have not seen a diagram of the HVAC case, but I'm fairly certain you can direct heated air to whichever vent you choose. In auto it will use the floor vents for heat and the panel vents for A/C.

We bought the car in mid April and live in Houston, so we definitely have not needed to use the heat. It has always been set to cold, yet E-Heat randomly comes on, and we know it does because the battery drains faster (I like to monitor the miles/kw used).

 

[jojomontag]

The HVAC system does monitor the humidity level in the car, and if it gets too high it will change the strategy, which may include switching to a dehumidification mode where both the heat and A/C are run at the same time. I'd imagine if you let it run for 10 minutes the heat usage would eventually decrease as the humidity drops. If you live somewhere humid, it's probably normal to see both heat and A/C on.

You have to remember in a normal car the heater core is always hot with the engine and is used to warm the air up to the desired temp after the A/C core. On the Mach-E, the amount of heat and cooling can be adjusted independently, so it's possibly only a small amount of heat is being used. Either way probably not a big concern unless you are trying to push your range.

Try to get in the habit of leaving your set temp in the same place all the time in auto, typically 70-75ºF to minimize energy use. The car knows best, sometimes using recirc with heat will use less energy than full outside air with A/C only, especially if it's really hot out. I'd trust the Ford engineers on this one.

I almost always use the departure times/precondition cabin feature (plugged in at home). And my temp is always set at the same, and we like using the recirculation setting because we don't enjoy the fumes from the other vehicles on the road. Not sure why the heat would need to come on at all when the feels like temp outside is 100°+. And the E-Heat does not utilize the vents. It radiates heat through the floor. According to the manual, in hot Temps, it shouldn't even come on, let alone operate at any level that would sap my efficiency (from 3.8-4.4 miles/kw to 2.7-3.1 miles/kw). That's a huge drop. The AC doesn't even affect my range like that (and I use it all the time).

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

I know we should be able to trust the Ford engineers, but it's kind of hard to do so when I have already had a service vehicle soon light come on so soon, and the techs at the EV Certified Dealership can't tell me anything because they have to play email tag with a Ford engineer. These engineers/Ford should have properly trained the techs at the dealership. Now I have a lovely car payment for a car I cannot drive.

 

[jojomontag]

I have not seen a diagram of the HVAC case, but I'm fairly certain you can direct heated air to whichever vent you choose. In auto it will use the floor vents for heat and the panel vents for A/C.

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

 

[Mach-Lee]

I almost always use the departure times/precondition cabin feature (plugged in at home). And my temp is always set at the same, and we like using the recirculation setting because we don't enjoy the fumes from the other vehicles on the road. Not sure why the heat would need to come on at all when the feels like temp outside is 100°+. And the E-Heat does not utilize the vents. It radiates heat through the floor. According to the manual, in hot Temps, it shouldn't even come on, let alone operate at any level that would sap my efficiency (from 3.8-4.4 miles/kw to 2.7-3.1 miles/kw). That's a huge drop. The AC doesn't even affect my range like that (and I use it all the time).

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.

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