OK, now that I have tackled the vacuum leaks and gotten the heater and various air vents working, when I put the selector to A/C the compressor does not turn on. I have the FSM and there are a lot of tests that can be run.

I was wondering if any A/C guru's out there might have a logical series of most likely things to check. I have not owned the car for even two weeks yet but my assumption is that it's a stock A/C system in my 77 280z.

If all of the R12 has leaked out, do the compressors have a built in safety to keep them from running dry?

It's gonna get hot here soon, so I need to jump on this one..

Thanks!

If it's a factory system, it will have a low pressure switch. If it's a dealer installed/aftermarket system, it may or may not. The switch doesn't keep them from running dry, it keeps them from running below a certain pressure. Take a close look at these two scans to determine which system you have:

Based on your pics, it's definitely factory air. So, it could be as simple as too little or no pressure?

can a shop still recharge these with R12 or do I have to swith some parts out?

thanks

You would need to have it checked to see why it has no pressure. Refrigerant doesn't evaporate from the system and I doubt if anyone would have let it out if the system was good. You most likely have a leak somewhere in the system. Usually it's one or more of the hoses. R12 is what that system was designed to use and it's the best way to go but it's expensive. Whatever you do, don't let anyone convince you to convert it to R134a. That kills these old systems. One good R12 alternative is Johnsens Freeze 12. That's what I use but I'm a liscensed MVAC/HVAC tech. You'd have to find a shop that uses that refrigerant.

So my best bet is to just take in to a shop that handles R12 or it's equivilent and not tinker with it? Let them do the diagnostics on it?

Thanks Stephen!