New A/C compressor locked up after not operating for 6 months

[edahall]

I've got a 1989 Dodge D250 with a 5.9 Cummins diesel. Last year, I installed a new A/C compressor and replaced the dryer and condenser. All was working fine on the A/C and then I ended up letting the vehicle sit for 6 months. I then got the vehicle running again. I then attempted to run the A/C but the A/C compressor was locked up so tight that it killed the engine. What happened here?

Here are a couple of photos of the compressor

[JohnHere]

I presume that this original R-12 truck was converted to R-134a and not kept R-12. If it was converted, how did you deal with the oil?

[edahall]

I presume that this original R-12 truck was converted to R-134a and not kept R-12. If it was converted, how did you deal with the oil?

Yes it was originally R-12. I flushed it out completely and used PAG oil.

[Tim]

Contact your supplier for a warranty.

Hard to understand the situation. Compressor and vehicle if never run during this time. Should not just lock up. Unless you left the system open during this time.

"All was working fine on the A/C, and then I ended up letting the vehicle sit for 6 months. I then got the vehicle running again. I then attempted to run the A/C, but the A/C compressor was locked up so tight that it killed the engine".

[Tim]

Maybe I missed it. I read it as it was locked up after sitting.

[JohnHere]

Maybe I missed it. I read it as it was locked up after sitting.

I'm not clear on that, either. OP, did the compressor seize after you ran it a while and after the six-month hiatus or was it locked up immediately on starting the engine?

I noticed in one view that the pictured compressor has a 1/4" fitting (not ACME) on the back, suggesting that yours might have come set up for R-12 and pre-charged with mineral oil. If so, did you drain the mineral oil and flush with PAG a few times before refilling the compressor with the proper amount and grade of PAG?

If that wasn't done, you had an oil incompatibility issue, which could have caused the new compressor to seize.

[Dougflas]

Original post states system worked fine and went bad after sitting 6 months. Also, rear fitting may be for a low charge switch thus 1/4 inch flare fitting.

[edahall]

Maybe I missed it. I read it as it was locked up after sitting.

I'm not clear on that, either. OP, did the compressor seize after you ran it a while and after the six-month hiatus or was it locked up immediately on starting the engine?

I noticed in one view that the pictured compressor has a 1/4" fitting (not ACME) on the back, suggesting that yours might have come set up for R-12 and pre-charged with mineral oil. If so, did you drain the mineral oil and flush with PAG a few times before refilling the compressor with the proper amount and grade of PAG?

If that wasn't done, you had an oil incompatibility issue, which could have caused the new compressor to seize.

The compressor locked up immediate upon starting the engine. Six months prior, it worked fine. The compressor came pre-charged with PAG oil.

[ice-n-tropics]

Might unstick frozen sanden knockoff by jogging engaged clutch both direction with 3 oz refrigeration mineral oil in crankcase
hotrodac