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

Posted: Mon Feb 08, 2021 4:25 pm
by 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

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

Posted: Mon Feb 08, 2021 5:11 pm
by 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?

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

Posted: Mon Feb 08, 2021 8:40 pm
by edahall
JohnHere wrote: Mon Feb 08, 2021 5:11 pm 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.

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

Posted: Tue Feb 09, 2021 9:00 am
by 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".

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

Posted: Tue Feb 09, 2021 1:22 pm
by Al9
A compressor needs oil to not seize up. Especially this compressor design, inside of which a set of piston shoe bearings ride the edges of a swash plate. Picks oil from the suction refrigerant stream. Not enough oil in the right places at the right times, and things start scraping almost like a fingernail on a blackboard, until something falls out of place and then everything plain seizes up.

The only plausible way of failure could be that, at startup, very little or no oil was inside the compressor's crankcase, and the evaporator didn't return enough of it in a timely enough fashion. Oil migrates with refrigerant across the system. 6 months of never operating AC may not kill a comp, but it does no good at all.

IMHO, insufficient oil charge and/or a refrigerant leak could be possible reasons. But i could be wrong.

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

Posted: Tue Feb 09, 2021 1:27 pm
by Tim
Maybe I missed it. I read it as it was locked up after sitting.

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

Posted: Sat Feb 13, 2021 9:22 am
by JohnHere
Tim wrote: Tue Feb 09, 2021 1:27 pm 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.

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

Posted: Sun Feb 14, 2021 5:17 pm
by 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.

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

Posted: Sun Feb 14, 2021 10:05 pm
by edahall
JohnHere wrote: Sat Feb 13, 2021 9:22 am
Tim wrote: Tue Feb 09, 2021 1:27 pm 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.

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

Posted: Mon Feb 15, 2021 2:40 am
by Al9
How much is the question. I've heard of (let's specify some) new comps stating pre-charged yet turning up with less than the system amount of oil inside. Good habit is to drain any oil out of the new comp, dispose of any drained oil properly, and then refill it to the proper amount with commercial DEC PAG (even better, flush the comp with cheap Ester AC oil beforehands). With some, unfortunately, all you have to do is flush the system as best as possible and then trust whoever did the initial oil fill (drain hole-less Denso 5SE09 comps, for example).