Air con misdirection.

[Group Captain]

2019 C220d Having trouble with aircon. I go to change flow direction from face to feet. There is a slight blow to feet but still blowing to face. This happens irrespective of whether hot or cold is chosen. But then after a couple of minutes at top flow level 7, it suddenly does as it has been requested. Any ideas? Any simple fixes?

 

[Trickythemerc]

Sticking blend flap motors.

 

[Petrol Pete]

Most decent scan tools will tell you if the blend flap motors are in the correct position.

 

[ALFAitalia]

Lots of cars have a DIY flap reset sequence too.....on my car its just disconnect/reconnect the battery and sit with the ignition on but engine not running for two minutes....you can hear the flaps running through their full movement and resetting. Not sure about this on a Mercs though as none on mine have has this issue. Since they do work correctly after a while it hints as either sticking or them not "knowing" their closed/open positions.

 

[Trickythemerc]

There is a reset button press fix for blend flaps, can't remember it but a quick google should give you a clue.

 

[whitenemesis]

This was for the 2005 W203 but may work on later models

Flap reset by holding down the RECIRC and DEMIST buttons for approx 5-7sec. Both should start to flash and all the flaps cycle. Can take 45-60sec to complete. On completion IGN off, wait ~40sec and switch back on
If there is an issue the cycle will not complete, just press either button again.
Best option is to get the car on STAR, codes read and flaps normalised.

 

[noogieman]

This was for the 2005 W203 but may work on later models

Flap reset by holding down the RECIRC and DEMIST buttons for approx 5-7sec. Both should start to flash and all the flaps cycle. Can take 45-60sec to complete. On completion IGN off, wait ~40sec and switch back on
If there is an issue the cycle will not complete, just press either button again.
Best option is to get the car on STAR, codes read and flaps normalised.

Would this reset work on all Merc's with ECC system even older cars like w202?