Air conditioner blower problem

[slowman]

I have unique problem with my 07 X5 AC. Driving along wit hAC in auto mode the system will switch to defroster mode and start blowing hot air on it's own. The only way to stop this is by pressing the fan button and then it will switch back to blowing cold and through the dash vents. Anyone else have this problem?

[bmrboi2]

What is the weather like when it does this?

Mine only does that when its raining or damp outside and it did the same thing in my old 5-series and the current 5-series. If that is what you are referring to, it is a normal operation of the system.

[slowman]

Originally Posted by bmrboi2

What is the weather like when it does this?

Mine only does that when its raining or damp outside and it did the same thing in my old 5-series and the current 5-series. If that is what you are referring to, it is a normal operation of the system.

I does this more often when it's 85+ degrees. It just started doing this recently before it was operating fine. if it was anything but a BMW I would guess it's a vacuum hose leak that causes the vents to change. But then again with a BMW if it's a vacuum leak you would expect a CEL. Car is an only has 80k miles..

[bmrboi2]

Im at a complete loss.

[Doug Huffman]

Condensation Sensor Program
The following conditions must be satisfied for the condensation sensor to operate:
• The engine must be running
• The IHKA must be in automatic mode
The IHKA control unit evaluates the condensation sensor signal (humidity). If condensa-
tion on the windscreen is imminent, the following measures are initiated in sequence to
prevent condensation from forming:
• Open defrost flaps further.
• Switch from air-recirculation/AUC/automatic air-recirculation
mode to partial fresh-air mode.
• Switch from partially fresh air in air-recirculation/AUC/automatic
air-recirculation mode to fresh air.
• Increase blower air volume.
• Reduce air volume for the footwell.
• Increase desired temperature value.
If one measure proves to be ineffective, the next measure is initiated. Once successful,
the measures previously performed are reversed step-by-step in reverse order.