I have a 1998 Volvo (S90). The problem is that the AC starts fine and while driving it stops and start blowing hot air. Sometimes, it takes about 10 to 30 minutes to goback to nomrmal, but in other occasions, it doesn't unless the engine is turned off for some time. Any suggestions.

I'm having the same problem I found this info here;
Cost about 10 bucks and took 5 minutes to install. It's called the ambient air sensor. Not to be confused with the sensor for the outdoor temp gauge.
at http://www.brickboard.com/RWD/index.htm?id=1083872
I think I'll give this a try.







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1996 964 170,000 Miles

Where is the sensor located. I just purchased a S90 '98 several weeks ago and notice the same problem to some degree.

I had a similar problem to this once and it turned out to be a loose wire connector to the clutch on the ac compressor. There's a wire going to the compressor that powers the magnetic clutch. If you remove the compressor, you can unplug the wire. However that plug may get dirty and worn and break the connection and reconnect several times in a hour. I cut it out and butt spliced the two wires and that was the end of it. Start the car and turn the ac on. Lift the hood and watch the compressor to see that it is spinning ( not just the pulley but the whole clutch ) and not turning on and off erratically. Also check the pressostat which is mounted on the reciever/dryer. It may sense low pressure and shut the system off and then change it's mind and turn it back on. It's cheap to replace but if you are borderline pressure it may be trying to tell you something.

Hi Sam,

I recommend reading thru the following two threads and see if you can glean any answers.

http://www.brickboard.com/RWD/index.htm?id=1081645

and

http://www.brickboard.com/RWD/index.htm?id=1081067

DEWFPO
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1998 S90 077,400 and 1995 964 154,100