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2003 Volvo XC90 T6 Air conditioner problems

At highway speeds AC cuts out and cannot be re-engaged even manually. Compressor is OK, cold air blows out of vents fine when first starting but stops blowing altogether after a while of driving even though cabin is hot. Cabin Air sensor tested ok. Please let me know if anyone has had this problem and what is the fix

Thank you!!

Is the compressor still running when this happens? Is air, hot or cold, blowing out of any vent? Is the blower fan running? Does the heater work?

Compressor works, initially cold air blows from all vents as required in “auto” mode. Then no further air comes out of any vent. If I manually turn the fan to a higher position, it responds (in the background) with more fan sounds, but no air comes from vents. in winter, heater works fine. Also, if car id turned off - started again - cold air will blow well. However, it does not quit when the cabin temperature has gotten to comfortable cool temp but from some mysterious cause. In a Volvo forum, a couple of people had written in with a similar problem occurring only at high speeds on a longer ride ( more than 25 minutes) and they reported a faulty sensor downstream from the compressor. How can we diagnose further??
Thank you

If you are still out there?? update: dealer had car with computer and sensors attached - highway tested but at legal speeds/not 70-80mph. he could not get air conditioning to fail. Yet owner of dealership a professional race car driver seems to see a relationship between high RPM and the coolant system conking out - any ideas??

Perhaps one answer is to keep you speed below 70 mph. Since you drive faster than that and like to stay cool too perhaps the rpm cut out switch is working too well. The AC compressor is turned off when you put your foot down on the gas to provide full power for acceleration. It seems your system maybe oversensitive and cutting your AC off prematurely.

Otherwise there all kinds of gates to allow cool or hot air into the car under the dashboard. At high speeds perhaps the air pressure in the vents is pushing one of these “gates” into the wrong position and diverting the cool air and keeping it from reaching the cabin. The bad news is that servicing the vents and gates under the dash is major work just to get to them and you don’t know if this is even the problem.

So, check out the switch to turn off the AC compressor during hard throttle. Then consider buying a new AC control unit that is pretty easy to take out the old one and replace it with another. These units are available on ebay for much less than a dealer replacement. Perhaps one of these actions will solve the problem. Until then slow down and stay cool.

Dear Uncle Turbo,
Thank you for your sage advice -I’ll pass this along to the dealership as well.Hard for me not to be a lead foot with all that turbo power, though :}