Sometimes it works great nice cold air coming out of the vents but if its been running for a while all the sudden it starts warming up .. the problem is is that after running it for another 15 or sold 15 to 20 minutes it seems to turn off and starts wa the problem is that after running it for another 15 or so 15 to 20 minutes it seems to turn off and starts warming up again has anybody had this problem. I have replaced the relay for the air conditioning and that seemed to help a little bit I am wondering if its the clutch cycling switch or maybe I have too much freon in the system does anybody have any or know where to look for the high side pressure hose.

 

I am having a similar problem. Mine blows cold until I accelerate then it blows warm and stays warm for about a minute then might blow cold. A/C relay? Any help will be appreciated !

 

Follow up. Freon full. Pressures are normal.

 

does it do this more on humid days vs dry days? (If so, I'm wondering if it could be icing up ). compressor clutch gaps being out of spec can also cause the compressor to cut off and will cut back in when it cools off. Next time it cuts out, try and see if you can tell if the compressor clutch is engaged (ie visual check or sound).

 

A/c systems are designed to shut off during hard acceleration that may be why yours goes warm. That should not happen under normal acceleration though.

 

my thought is also iceing up the problem I am having is i can only find the low pressure side fitting to hook up the gauges. I may have put to much freon into the system when I recharged it. Do you know where the high side fitting is so I can check pressures? I may also have some blockage in the line but I am not sure on that right now until I can get proper pressure readings.

 

I had a bad reading on my guages. All I needed was to top off the freon. Now works perfectly !!!

 

So where is the high side fitting? I am about 90% sure my freon is to full.

 

You should be able to check pressure on the low pressure side fitting on the return line since that's where you'd fill from. On my 850 the fitting is right above the compressor. You will want to measure the pressure when the AC compressor is engaged. If its not engaging you may need to jumper the low pressure sensor which is on the return tube nearer to the firewall.

 

low side pressure is about normal compressor is turning when the ac isnt working. with a high side reading I can determine if the compressor is still pumping freon or if there is a clog in the system.

 

The high pressure fitting for my 2003 Volvo xc90 is on the passenger side of the car, passenger side of the condenser up top. I looked for this forever and thought there wasn't one for a year. Hope that helps someone!

 

This sounds like the air gap in the clutch has become too large to engage when the clutch gets warm. It is a common problem and not too hard to fix.

The quickest way to check this I have found is to feel the clutch relay in the box when it isn't working. It will be super hot to the touch. Remove the shim from the clutch face and replace the relay.

 

check the temperature sensor inside the car. For auto Mode. That's what was wrong with mine. 09 C70