Strange AC issue: software root cause?

[MBK_BKLYN]

Over the weekend we had very high temperatures in NYC, upper 90s. While driving the AC in my X seemed to die. Only hot air blowing from the vents, no matter what the temperature setting (I had plenty of charge and Range Mode was off). On my way home it was hitting 110 degrees in the cabin.

I made an SC appointment for today. On my way driving over today it seemed like the AC might be working a tiny bit, but after about 20 minutes of driving seemed to blow ambient temperature air, no matter what the setting. Either it worked barely for 20 minutes, or it was an illusion because the car was cool (I park underground).

The SC is great, handles the parking brake recall, rebadges my car to the upgraded 75D (had upgraded that a month ago), apparently does a software update (according my phone notifications), but can't reproduce the AC issue. They say it's blowing cold air. Remotely I verify this: the app shows the cabin at about 79 degrees, I turn on the AC and see the temperature drop to 68 in the course of a few minutes.

So, either I had a weird software issue that the update solved, or I've got an AC issue that manifests after driving for a little while. SC is keeping the car overnight and will try driving a bit tomorrow and see if the issue can be reproduced.

Has anyone else experienced an issue like this? I'm stumped!

 

[animorph]

Quite possibly a reset caused by the update, or SC actions, fixed your issue. Always a good idea to try a reset when strange things happen.

 

[MBK_BKLYN]

Is there a way to truly reset the car? I tried the double-scroll-wheel reset, it didn't seem to work.

 

[MBK_BKLYN]

Well, SC said they couldn't reproduce. And it worked after that until today when it failed again about 15-20 minutes into the drive. Power off and screen resets didn't help.

Totally mystified. Back to the SC again

 

[jerry33]

I have heard of this happening in non-Teslas. The case that I heard about was the coolant lines not being connected correctly. This is hard to diagnose as the lines have to be traced. However, a simpler explanation is a faulty sensor somewhere causing the A/C to shut off.

 

[MBK_BKLYN]

When you change the temperature up and down the fan changes speed, so I think the cabin temperature sensors are picking up on things. But I don't hear the compressor going, so something is preventing that from kicking in. I don't think the compressor itself if broken, as the cold air worked at the start of the drive.

 

[MBK_BKLYN]

Today over two 15 minute drives the AC worked fine. The mystery deepens. Ambient temp was cooler than yesterday, but still in the low 80s. I wonder if it could be something with the car trying to cool the battery when it's closer to 90 degrees out? That would seem odd, but maybe some kind of battery chiller problem. Still going to call the SC tomorrow and see if they can pull the logs and check for any signs.

 

[animorph]

I have heard of this happening in non-Teslas. The case that I heard about was the coolant lines not being connected correctly. This is hard to diagnose as the lines have to be traced. However, a simpler explanation is a faulty sensor somewhere causing the A/C to shut off.

That was an X problem too.

I've been very happy with the A/C in my X here in AZ. The past week was all 110+ degrees F. I kept forgetting to turn on climate before reaching the car. But it only took a minute to cool down after leaving it in the sun in a parking lot. No problem reaching 70 degrees in the car in a few minutes.

From TeslaFi logging:

Outside temp: 114F
Inside temp:
Start: 98F (Temperature was logged as between 104F and 98F while parked with cabin temperature protection active)
1 min: 79F
2 min: 74F
3 min: 73F
6 min: 72F
8 min: 71F
16 min: 70F (set temperature)


The performance is there if everything is working.