Thanks for reading my post. I have looked over the all the 850 and S70 forums for information about AC problems (leaking evaporators, dirty temp sensors, busted ECC units, etc.) and can't seem to get a grip on the problem I'm having.

The AC on my 1998 S70 GTAS blows hot and then cold air intermittently only when I'm driving home from work in the afternoons. The problem occurs only when the outside air temp is above 90 deg F, at highway speeds, and after the car has been sitting the parking lot all day. There is no discernable pattern to the amount of time the AC blows hot and then cold. When I drive to work in the mornings, the air temp is usually below 80 deg F, I'm driving on the same highway at the same speeds, and the AC works perfectly. Just this morning I had to turn the temp up because it was blowing too cold.

I recently had the 70,000 mile service done, which I believe includes a check on the refrigerant level. None was added. Any ideas? Thanks.