I have a 94 Volvo 850 N/T. The heat didn't work this winter so i put a new thermostat in. Works great. Now my A/C is not working. I've been reading through everything on here and a couple things that seem common is that my compressor keeps cycling on and off and I get NO cold air. I hooked up one of the recharge kit guages and it read the PSI as normal (in the 20's. I squeezed a little more in just to see if that would help and it didn't, but I didn't put that much more in (still kept it in the can perscribed safe range). What is a safe charging range on this? I think I read somewhere else that I could all the way up to 40psi. What is safe for me to do to see if overcharging it will work?

 

You dont want to overcharge it. In fact, I dont think that is your problem. It could be: 1) AC compressor clutch, 2) the evaporator, 3) blower fan motor, 4) fan resistor, or 5) the ECC controller. I'd start my check with the clutch. It may need re-shimmed.

Here is some suggested reading on the subject: http://www.matthewsvolvosite.com/ac_page.php

Good luck!

 

Your system holds 1.65 lbs. The compressor cycling is good news that the pressure switches are working. Does your radiator fan come on? If so, it's hard to diagnose with out a set of manifold gauges. The low side with the fans operating will be around 30-35 psi. The high side should be around 225-250 psi. A proper set of manifold gauges will set you back $250.00 from the local Snap-On dealer. It might be cost effective to pony up to your local shop for a evac/recharge if your threshold of pain is low.

 

+1 to checking the compressor clutch and having a shop evac the system