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AC not reliable in warm weather

Posted: Wed Jul 10, 2019 5:20 pm
by mantis
Hello all. I've got a FFE 2017 that I generally have no problems with.

However, whenever the car is 'out in the heat' for a while, the air conditioner becomes really unreliable. For example, entering the car after its been sitting out in 26degC+ (80degF+) weather is a guarantee for the AC to be fully functional for maybe 5 minutes, before starting to blow hotter and hotter air.

At this point, I might as well turn on the heater; the air from the vents is that hot.
Sometimes, fully rebooting the car or letting it sit for a little while causes the AC to be functional again, for around the same amount of time.

Has anyone else experienced this? Is this something to do with cooling of the batteries?

I thought about going to the dealership, but my confidence in them being able to diagnose properly is... slim. Also, whenever the weather is calmer, the AC works perfectly fine. Any cooler and it is freezing cold.

Re: AC not reliable in warm weather

Posted: Wed Jul 10, 2019 11:52 pm
by kalel14
In hot weather, the cooling system prioritizes cooling the HV battery before cooling the cabin. So the air conditioning compressor is running, but it's not your turn to get cold yet. After the battery temp is at a manageable level, cold air is diverted to you. This is normal.

Re: AC not reliable in warm weather

Posted: Thu Jul 11, 2019 3:54 am
by scottt
Surprising though. It's been in the 90's here for a bit. I'll usually remote start, however even if I don't I get frigid air immediately out of my AC. Love the AC in the FFE. I could store meat in the car in the middle of summer with no issue.

Re: AC not reliable in warm weather

Posted: Thu Jul 11, 2019 4:10 am
by mantis
kalel14 wrote:
Wed Jul 10, 2019 11:52 pm
In hot weather, the cooling system prioritizes cooling the HV battery before cooling the cabin. So the air conditioning compressor is running, but it's not your turn to get cold yet. After the battery temp is at a manageable level, cold air is diverted to you. This is normal.
Thanks. Should I be leaving the cabin AC on, or will leaving it off have the same effect?

Re: AC not reliable in warm weather

Posted: Thu Jul 11, 2019 4:34 am
by kalel14
The car won't cool the cabin until the battery is happy, so you'll get warm air if you leave it on. But there's no indicator the battery is happy, so you'll never know when it's ready for you to turn the air conditioning on.