[VAB5]

Good afternoon folks,

I have a head-scratcher with my AC this weekend on a road trip.

Observed with ambient temperature above 80F, all driving on the interstate.

If I start off in Auto mode at 70-72F, after about 10 minutes the system starts blowing cold-ish air. It's still somewhat comfortable, but doesn't seem to keep up. Even increasing fan speed and decreasing temperature doesn't help. Vent output seems to be reduced as well. Eventually it becomes too warm in the car.

Without shutting off the system, moving to Max A/C helps for a bit, but then seems to make more noise than fan output at the vents. Comfort level is bearable, but not great.

Stopping the car for a few minutes (think a highway rest stop) restarts the cycle--system works normally with cold air and good vent output, then not-so-cold air.

However, if after stopping I go directly to Max A/C, it stays cold--we did a 2.5 hour span where it stayed ice cold. I had to turn down the fan speed because it was so cold, even though it was above 90F and full sun.

Same drive (no stop), put system back on Auto, and it went back to being no-so-cold anymore after about 10 minutes.

Any ideas? The fact that starting with Max kept the temp cold leads me to believe it's not an A/C charge issue. Other than that I got nuthin...

Thanks!

[Surly73]

If I were in this situation I would:

1/ scan the car with a BMW scanner and look for any codes stored from the IHKA
2/ look at the manual and go back to first principles with everything on the AC - check that you don't have any of the face vents pointed back down at the AC unit (drawing in ice cold air from the vent fooling the unit into thinking the inside of the car is that cold), point all the vents straight out blowing PAST your face not into it, set all the blend wheels (red/blue dot wheels next to many of the vents, depending on how the vehicle is equipped) in the middle, set the system to AUTO with the fan speed in the middle and a reasonable temperature (like 72) on both sides (or all four if backseat system is equipped), then see what happens.
3/ override recirc to on (not off or auto) if it's humid outside

I'd agree, the constant performance in MAX does seem to point to something other than charge, but that's still a possibility. I see so many interior shots of people running with everything overriden - set for min temp on one side, 80F on the other, vents and floor manually selected, blend wheels at full cold but the vent pointed straight down, then post on the Internet that stuff works weird...