Needing some insight. I have a 2003 XC90 with the climate control system. My A/C seems to shut off the vents after the car heats up. Strange thing is the A/C fan is still running, I just don't get much air flow from the vent. A/C is cold. This problem exists in either the auto mode or the manual mode.

Any ideas what is happening?

 

If the A/C system isn't able to keep the desired temperature inside the car, and the air flow is poor, the air filter needs replacement. If the air flow is good at first and then becomes less and less as the temperature gets close to the desired value, that's how it should work.
If the regulation is poor, try cleaning the sensor air intake (small opening) near the right temperature set point ****.

 

From the time I purchased myXC90 a couple years ago, until just a month or so ago, I had poor performance from the HVAC system. In addition, I had a high-pitched whine that increased in sound as the blower went faster.

Well, I went to check my cabin filter as normal maintenance last month and... hey, look at that... whatever monkey was in there before me unscrewed two of the for Torx screws that hold the cabin filter cover plate on, but just BROKE OFF the back two.

That let the back part of the cover hang down a bit, making the air whistle / whine that I had been hearing. Replacing that cover, a $5 part, made the whistle go away and made a HUGE difference in the ventilation system's effectiveness. I just thought the XC90s HVAC was a little undersized, now it is perfectly adequate, even in hot summer weather.