Will an A/C compressor engage is there no refrigerant (pressure) in the system?
 

I have not used my A/C since I bought the car over 14 years ago. It was converted to R134 by the PO. That being said it was barely discernible whether it was actually "working" when I brought it home. I don't care much for A/C and so I simply removed the compressor belt.

Now I'm curious to get it going again. I have no idea if there is ANY refrigerant in the system. I was told an A/C compressor clutch would not engage if there was no pressure in the system. I installed the compressor belt and only momentarily turned on the A/C to see if the compressor clutch would engage; and so it did! The clutch engaged. I only let it run for 1-2 seconds to see if it would engage. I don't want to run the compressor and damage it if there is no refrigerant or not enough. So, does this mean my A/C system is pressurized?

Thank you,

Well, different car/system - but when I bought my 944, the A/C clutch would engage if the button was pressed, but it didn't go cold.

After a few years, I figured it'd be useful for getting fog off the windshield or a hot day, so got it checked out; apparently all the refrigerant was gone, like the PO had said. Had the system pressure checked and re-filled - all fine.

If no previous owner added a high/low pressure switch to your 911, then the compressor clutch will engage if the system is completely discharged or even if it is full of goat pizz (aka - no pressure switch installed by the factory - who knows why as they were widely in use when your 911 was made).

no it does not mean it is pressurized.

you need to put gauges on it to check.

I would not try to run a system that has sat for 14 years. It's full of humidity, the oil that was leftover has turned to goo, there is probably rust inside the system...basically, it'll be a mess.

That system will require complete dismantling and examination of each part.

I could only imagine how long my 86 comp did not run. just got it going 2 weeks ago.

it should not have humidity in there unless it was opened. then I would just drain the oil and replace.

Any idea how long yours didn’t run? (Ballpark?)
Ya, I don’t think the sky is falling, but I may consider rebuilding the Denso compressor just to freshen up the seals and such. Then I have one hose I will want to replace because it has chafed against the engine lid hinge.

A/c
 

I have PM you, this may help.