A/C Turns Off at 100mph

[Garbone]

Standard Range or Ex Range pack?

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[Neil4Real]

Standard Range or Ex Range pack?

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[Scarpia]

So... I did a thing and wanted to, uh, you know, make sure my car really did not go any faster than 113mph, like I've read. For science, of course. Well, I had my A/C on auto, 1 "notch," and right when I would hit 100mph it would turn off. I tried it with Auto on max, 3 notches, and it seemed to actually stay on full blast and remain cold. But then when I slowed back to normal speed, the interior of the car smelled pretty weird, almost like a gas smell... any ideas on bothitems?

Mine was good to 130, so I would def get that checked out at the dealer.

They may have to road test it to recreate the problem, though.

 

[Neil4Real]

Mine was good to 130, so I would def get that checked out at the dealer.

They may have to road test it to recreate the problem, though.

Good to 130mph? Do you have a GT? The non GT Mach-e’s definitely stop at 113 and cannot go above that speed. So I’d say your car probably needs to be checked xD

 

[Mach-Lee]

Makes me wonder, at that speed the air could be thick enough not to be pushed or pulled into the front louvers, the fan pulling could be pulling dead air. Ide like to see it in a wind tunnel but I suspect that it turns off the AC because it has to cool the battery more actively with less air. Might also explain the slow to high difference as the coils would be much cooler on high due to extra condensate forming from more air moving across the coils.

Couple thing here from an engineer's perspective. Air does not get measurably "thicker" when traveling fast through it, at least not at the speeds you're talking about (we're not breaking the sound barrier here). What happens is flow increases through the radiator/condenser from the increased speed and frontal pressure, not the opposite. The car can open and close the grille shutters to adjust the flow if needed. Also not sure what you mean about the condensate, that happens inside the dash in the evaporator, airflow through the evaporator is controlled by the blower fan irrespective of vehicle speed.

So, this sounds just like what happens when you go WOT in any ICE vehicle made after the mid-late ‘80s or so. In those cases the AC compressor is shut off under full throttle to allow maximum power for passing or whatever you’re doing. I’d assume the MME is doing this to allow the HV pack to deliver max juice to the motor(s).

The amount of power it takes to run the A/C compared to propelling the car is TINY. If you were cruising at 100 MPH constant with A/C going full blast you would only be using 10% of your energy for A/C at the most. The A/C takes 1-5 kW and the car might use 200 kW accelerating. So it's probably not cutting out for power management.

My best guess is the car is diverting cooling for the pack. The A/C has solenoid "switches" that can turn on and off cooling to the battery and the cabin. At high speed/load it's probably shutting off the cabin so the battery pack gets the full capacity of the compressor. It would be interesting to see if this still happens at moderate temperatures (say 60ºF) with a cool pack or if there is a threshold temperature component to the strategy.

 

[Trick.Mach-E]

We had no A/C problems in 105° TX heat while cruising at 96MPH to 113MPH. The A/C was on auto (1) set to 69°.

 

[Neil4Real]

We had no A/C problems in 105° TX heat while cruising at 96MPH to 113MPH. The A/C was on auto (1) set to 69°.

So it seems to just be more software issues related to my vehicle from when they did my instrument cluster screen replacement... what a bummer. Thank you for bravely testing this out!

 

[prdude]

Couple thing here from an engineer's perspective. Air does not get measurably "thicker" when traveling fast through it, at least not at the speeds you're talking about (we're not breaking the sound barrier here). What happens is flow increases through the radiator/condenser from the increased speed and frontal pressure, not the opposite. The car can open and close the grille shutters to adjust the flow if needed. Also not sure what you mean about the condensate, that happens inside the dash in the evaporator, airflow through the evaporator is controlled by the blower fan irrespective of vehicle speed.

My best guess is the car is diverting cooling for the pack. The A/C has solenoid "switches" that can turn on and off cooling to the battery and the cabin. At high speed/load it's probably shutting off the cabin so the battery pack gets the full capacity of the compressor. It would be interesting to see if this still happens at moderate temperatures (say 60ºF) with a cool pack or if there is a threshold temperature component to the strategy.

Actually, if the climate system is operating in fresh air mode, there can be a ram air effect of additional air feeding into the HVAC from the cowl. But the OP was in auto mode, which pretty much forces recirc mode, whenever a/c is running, and thus blocks off the cowl.

I would be surprised, if a/c got shut off to increase compressor capacity for the chiller. I don't believe the chiller could actually handle the full mass flow capacity of the compressor.

 

[Neil4Real]

Actually, if the climate system is operating in fresh air mode, there can be a ram air effect of additional air feeding into the HVAC from the cowl. But the OP was in auto mode, which pretty much forces recirc mode, whenever a/c is running, and thus blocks off the cowl.

I would be surprised, if a/c got shut off to increase compressor capacity for the chiller. I don't believe the chiller could actually handle the full mass flow capacity of the compressor.

Auto forces recirc mode? Does recirc mode actually shows as on though? I only use auto and recirc button is always off, I have to manually turn it on every time. For my "test," recirc mode, at least the button, was OFF, so it was bringing in air from outside.

 

[prdude]

Auto forces recirc mode? Does recirc mode actually shows as on though? I only use auto and recirc button is always off, I have to manually turn it on every time. For my "test," recirc mode, at least the button, was OFF, so it was bringing in air from outside.

yes, Ford auto modes mostly use recirc, because it reduces power consumption. I'm not sure how consistent Ford is vehicle to vehicle, in terms of whether the recirc light is illuminated. From what you're saying the MME doesn't illuminate the button.

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