Sorry if this issue was covered elsewhere on his forum, but I didn’t find it.

I have a 2003 XC70 with A/C problems. The air doors close at random times. You can hear the fan blowing strong, but very little air is escaping the vents. You can turn the temperature to its coldest setting and turn the fan up as high as possible and get some residual air that escapes the doors, but on a 90 degree day it will not bring the cabin to a comfortable temperature.

I took it to my local air conditioning specialist. They were unable to replicate the problem in the shop. I spent $850 while they tuned up/rebuilt everything, but the air doors still close at random. This acts similar to the old school vacuum system when a vacuum line began to leak, but they assure me that Volvo does not use vacuum lines to open and close those air doors.

Can anyone give me some indication of what part is failing here?

 

They took you for $850 when they didn't know the problem? Ouch.

You'll need a dealer or VIDA. Might just need a software upgrade. Might need the damper motors calibrated. Might need one replaced.