If the clutch works, and the pulley spins freely, the compressor is OK, right?

 

Not necessarily. The compressor can have leaking external seals, so the system will not hold a charge. The bearings in the compressor can be bad. The internal seals can be bad, so that the system cannot compress. What symptoms are you having, and what are you assuming that "the compressor is ok" means in terms of what you think is wrong?

 

The clutch doesn't enguage when I turn the AC on, BUT the system has very little charge... (it sat for 3 years before I bought it, and I think it was low before that)

I'm just making sure I won't put my precious r-12 in only to find that I have to dump it to replace the compressor...

 

Thats where a recovery system comes in handy. Load it check it if it does not work take it out. Diyers don't have that luxury.

 

Will the recovery system be able to load the r-12 back into my system? Or is "recovery" just the same as "storing for the freon man to take to the great ozone bucket in the ground"? I'm not planning on doing it myself, as I don't have the $100 deposit to rent the guages from autozone, and certainly can't afford them myself...

 

Recovery systems can store and reuse R12.

If +12 volts directly to the clutch makes it engage, it is fine. If it is not coming on in spite of checking out OK with direct voltage, look to the low pressure switch. Modern systems usually route the clutch wiring through a pressure switch in the tubing near, or on, the condenser. The clutch will not engage if system pressure is too low. (There is a hi pressure switch also, usually built into the accumulator system). If a direct test shows the clutch is ok, find the low pressure switch with its two wires. It is safe to pull these wires off and jumper them together briefly. See if the clutch now engages when you turn the ac on. You don't need to start the car to do this test, but if you do - Do not run the system with low pressure for more than a few seconds!

Most cars route the clutch wiring through a relay. If the clutch won't engage but passes the above tests, look for blown fuse or bad relay. Then, there can always be a problem with the ac control unit in the dash. And, most modern cars cut the ac at WOT (wide open throttle). So the clutch engagement is also routed through the PCM (engine computer) which usually is told of WOT by the TPS (throttle position sensor). However, this system is probably the least likely to be at fault.

Common things are common. If the clutch itself is ok, and you know the system pressure is low, the fact the clutch won't engage is most likely due to this low pressure. Fix the pressure and the clutch will engage.

 

That's what I wanted to hear Should be going to get it recharged today or tomorrow...

Thanks,
Rick