The A/C on my 2008 c30 T5 not working well. Freon was low causing compressor to kick on and off. Found both Schrader valves leaking. Replaced, vacuumed and refilled. Now system blows cool but not cold. Also noticed that the high pressure side is all over the placed. At idle it can go down to 190 psi and sometimes around 245 psi. When driving down the road it runs about 200 psi up to 275. This is with the controls set to max cold and max blower. Any one have any ideas. Could this be the compressor going or maybe an expansion valve? Any help would be great.

Thanks Vun

 

Unstable pressures on the high side would be caused by the cooling fan not working properly as well as a high pressure cutout switch. The pressure switch doubles as a low pressure cutoff and high pressure release. In almost all cases, it never hits the high pressure side in normal operation. It cycles by hitting the low pressure side.

The expansion device can stick and give readings like you say. If the cooling fan is running and you get irregular cooling, I would suspect the expansion device.

 

Thanks for the info. Cooling fan is running. Will look at the high pressure switch and expansion valve. Also have readings from a scanner with live data. The evaporator temp stays at about 53 F And the compressor switch shows (on continuously) when the a/c is turned on. It never cycles on and off like my other Volvos.
Is there Some way to test the high pressure switch.

 

Until the cabin air fan settles down you probably won't get the compressor to cycle. If the interior cabin is hot, the thermal load on the refrigerant is high enough to keep the compressor engaged. As the cabin cools and the can speed goes down, the thermal load is less and the compressor will cycle.

If it doesn't cycle, it almost sounds like an overcharge condition to me.

 

Sorry hit the enter button before I was done.

Again thanks for the help. Will look a bit more if can not find anything will take to shop.

Thanks Vun.