"Air Conditioning Reduced" message

[SSonnentag]

I've seen the message a few times, usually when supercharging in 115 degree heat with the AC on. The car prioritizes the battery temperature over the cabin temperature.

 

[yngwiescruggs]

I just had this issue happen a week or so ago in my 2015 Model S. I left the climate control running at 81F on a blacktop parking lot, in the sun, in Phoenix, on a 115F day. When I came back to the car 15 minutes later I had this same warning. Within a couple minutes of driving the A/C was blowing hot - outdoor air or hotter. I was able to drive home (7 miles on 45 mph roads) and got no further warning messages.

When I got home I plugged it in and a fan (I think the battery cooling fan) continued running for over 48 hours continuously. It was quite loud. I turned the cabin overheat off as it was well over 105F inside. MCU and all other functions continued to work fine. I tried two-button reset multiple times but that did not help. A/C blew hot this whole time whenever I tried it. Weirdly I could not hear the A/C compressor running and the louvers remained closed. We got lucky that we had a monsoon storm so I opened the garage and blew fans in to try to get the car to cool down

Anyway after 2.5 days or so, the cooling fan turned off. Presumably this warning cleared when the battery temperature finally reached under some critical threshold. When I then tried again, the compressor turned on immediately and the A/C blew cold, no warning displayed. So far it seems to still be working. So at least in my case perhaps it was a software issue that was initially triggered by putting the battery in bad thermal conditions.

I have a service appointment in 2 weeks anyway and will see if service finds anything or can provide any further insights. But otherwise it appears to have resolved on its own once the battery cooled to a safe temperature.

Following up on this, in my case they ran AC diagnostics and identified the louvers as the problem so are going to replace them. They said all three failed their thermal test. No apparent issue with the compressor thankfully (no particulates in refrigerant, pressure OK). This is speculation but my battery degradation is worse than normal (we have rated 100% @ 233 mi on a 2015 85D with 117k miles) so I wonder if poor battery cooling perhaps has been a sub-critical issue for some time.

 

[Ghosty]

I just experienced this issue today: Car as listed in profile, below. Car was parked at gym, not supercharging in 113 degrees. Fan has been on for days since the heatwave began. Left garage door partially opened to keep garage cooled. Coincidently, I have a service appointment for the "soft recall" - screen and blinkers didn't work a few weeks ago. Sent a message in the Service App to include this message as an issue to look into.

I'm hoping the message goes away and I go on my merry way.

 

[tccartier]

Following up on this, in my case they ran AC diagnostics and identified the louvers as the problem so are going to replace them. They said all three failed their thermal test. No apparent issue with the compressor thankfully (no particulates in refrigerant, pressure OK). This is speculation but my battery degradation is worse than normal (we have rated 100% @ 233 mi on a 2015 85D with 117k miles) so I wonder if poor battery cooling perhaps has been a sub-critical issue for some time.

I'm only doing slightly better 2012 model S 85 signature seeing about 242 rated at 100% soc. My battery however was replaced in 2016. Current mileage about 119k. Battery was replaced at 30 something ish k miles so it has 85 ish. thousand miles on it.

 

[cybergates]

Had this same problem in 2018 — model S 2016 late build AP2

In 2018 they found it to be the infamous louver issue mentioned above and all is well now for the past 5 years….until today same thing happened. Knowing what was the issue last time - confirmed louvers shut - I was able to very gently press them open on both sides and stuffed a rag / towels to hold them open - they might have stayed open but I couldn’t chance it as I was traveling w some elderly relatives very sensitive to the heat. It worked - ac started working great!! While supercharging let it run and the car was down to an ice cold 60F!

Will take it in for service and see if it’s the same issue that they find - disappointed that the same issue is back - is it a known weak component to fail?

I’ve heard others mention this - avoid range mode —- and indeed range mode was on initially - but then disabling it didn’t fix it until I tried the hack above

 

[SSonnentag]

It turned out that my Model S louvers weren't opening, which was causing slow supercharging and reduced cabin AC.