hows it goin, i have a 96 volvo 850 wagon. i recently had the AC recharged and everything was working great. this past week its gone to ****, if im going under 50 mph the AC stays cold if i go over 50 say like im going a steady 60mph the AC will blow warm for like 15 seconds and then blow cold for 10 sec. i live in VA so its been in the near 100s all weak. Every time i hear the compressor engage i can also hear a high pitch sound coming from inside the cabin or at least sounds like its inside. it comes on everytime the compressor dose, im not sure if its a relay from inside the dash or what but i hear it. im not sure whats going on here with this AC system but if any can get an idea of what im talking please help me out. oh and where the AC switch is on the climate control the little light is RED not white, im pretty sure that indicates a problem. any ideas on that??? If you guys want i can make a video to give a better idea of what im talking about..

 

Have to take it to a shop that can read ECC codes; may only be the dealer.

 

If you had a manifold set with a high side gauge it would be helpful. It sounds like there is a restriction in there which would make the high pitch sound you are hearing. If it's restricted then you might be hitting the upper pressure limit and the pressure switch is shutting the system down until it bleeds off enough pressure to once again kick in and turn it back on. That high side gauge would tell you if that's what is happening but even so it isn't going to be anything you would realistically be able to do yourself.

Best bet, take it in to someone with a full set of gauges and experience. sorry

 

Didn't think these cars had high-side AC ports; am I mistaken?

 

No, most vehicles have a high and low side port for diagnostic purposes. The high side is the bigger of the two connections and the one that people come back and bitch about how the 25, 35 or 45 dollar cans of DIY freon don't fit their vehicle. It's like OBDII, they are all the same and if it doesn't fit it's because you're trying to hook up the connection to the high side

On our 850's they didn't provide a high side port I can find.

 

Thanks but I am well aware of where the low-side port is, but if you have a pic of the high-side port location, I would sure like to see it..

 

It's late, it's dark, climbed over and under and it doesn't have a high side port I can find. Every time I think I know what engineers do they go out and have a three martini lunch and redesign something.

Revised statement: almost all cars have both a high and low side AC port. Volvo is the first I've run across that doesn't but I'm sure if they deleted it others have too.