Over a month ago I got an S60 with 248,000 miles on it. I'm the 3rd owner; the 2nd got it at 10,000 and has done all the recommended maintenance since, and it runs great.

The previous owner said something about needing to charge the A/C often and that a $400 repair would've fixed it, but he didn't mind charging often.

It worked when I got it, but after 2-3 weeks the A/C stopped blowing cold, and my radiator fan started running on high at all times while the car was started.

It's also worth noting that I have a CEL for a small evap leak (P0442). I haven't diagnosed it yet.

I heard charging the A/C would make the fan stop running, so after dealing with the fan for a while I got AC pro.

When I checked the pressure of the system (low pressure port), it was 0. The compressor was running but the clutch wasn't engaging at all.

I tried charging it, and initially the pressure of the system would go up to about 10 PSI and the radiator fan would slow down (so there aren't issues with any controllers or sensors). But the pressure would go back to 0 after a few seconds, and the clutch still wouldn't engage. The cold weather didn't help, the can got cold quickly and lost most of its pressure.

I have no idea where to start. Any tips would be appreciated.

 

The low side should show about 25-35 psi and high side 150-200 psi depending on humidity. the 400 hundred dollar repair might be a leaking condenser. have a shop perform an evacuation and re-charge with black light dye so the source of the leak can be pin pointed. yes the cooling fan should be running but not full blast. could be an indication the ECT sensor integrated with the thermostat housing may be bad but can't say for sure.
As far as the code P0442 could be numerous things in the emissions system but start out with the basics like checking the gas cap sealing ring or if the cap is loose. otherwise could be numerous other things evap valve stuck open or close/ leak in an emission hose/leak diagnostic pump bad. will need smoke tested to rule out any hoses that could be split.
good luck, cheers

 

I'm thinking the fan and associated sensors are good since it behaved normally for a couple seconds when there was pressure in the AC system.

The guy I bought it from said he would have to charge the AC every month or something around there. Is it possible that a leak was causing that (possibly in the condenser) and it got worse to the point where the system can't even hold pressure for three seconds?

Thanks for the reply.

 

Try and get your a/c recharged with UV dye so you can pinpoint the leak. also since the compressor has been working so hard and Being low on Freon it puts a strain on the clutch because its almost always engaged i would consider a compressor especially if you're having pressure problems after the system is freshly re-charged. let me know how this turns out.
good luck, cheers

 

Stop charging an leaking system!, get someone to pressure check the system with nitrogen, and then locate the leak with soapy water, it's propably the condenser that's corroded or have been hit with a rock or something.

And as Josep said, your compressor could be toast, it's been turning around with out sufficient lubrication.

But take it to a shop, the r134a gas is really bad for the environment 1430 time worse than CO2 from you'r cars exhaust