[RobertoTaylor]

I have a 2012 535i and I've noticed something strange. In the mornings when I leave my house to go to work, the heater seems to only blow hot air when set to the highest temperature (84*) in Auto mode. Once the car is warm and the air is coming out hot, if I drop it to even 83*, cool air begins to come out of the vents instead of warm air.

We also have a 2015 X5 and the heater on that works as intended. The air temperature is adjusts as it should when you turn the temperature knob.

Has anyone else experienced this?

[philipm785]

Does your car have one (or more) of those blue/red adjustment wheels by the front climate vents? If so, you need to leave those in the center of their travel or the system will make the air coming out of those vents warmer or cooler (depending on the setting) than the auto set temp. The idea was to be able to blow cool air on your face while still heating the cabin, but it's always been a bit confusing. Just a thought.

If that isn't it, it could be a temp sensor since the system would probably disregard the temp sensor reading if set to max heat. If the sensor is reading high, any setting below max might cause it to switch to cooling since it thinks the car is already super warm. I've also seen external temp sensors cause the same issue (check the reading for outside temp on the dash to easily diagnose this one).

[RobertoTaylor]

Originally Posted by philipm785

Does your car have one (or more) of those blue/red adjustment wheels by the front climate vents? If so, you need to leave those in the center of their travel or the system will make the air coming out of those vents warmer or cooler (depending on the setting) than the auto set temp. The idea was to be able to blow cool air on your face while still heating the cabin, but it's always been a bit confusing. Just a thought.

If that isn't it, it could be a temp sensor since the system would probably disregard the temp sensor reading if set to max heat. If the sensor is reading high, any setting below max might cause it to switch to cooling since it thinks the car is already super warm. I've also seen external temp sensors cause the same issue (check the reading for outside temp on the dash to easily diagnose this one).

Thanks, I'll give that a try.