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A C Compressor Help Needed


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The PO gave me another compressor when I bought the truck because the one that was in it was bad, it actually worked but made a knocking sound.

 

So, today I finally got around to swapping it out, made it all purdy and everything.

 

It ran for about 45 seconds and then locked up, I was in the process of recharging the freon when it locked.

 

I cannot imagine I did anything to it in the process of cleaning it up or installing it. I did swap the clutch as the one on the replacement was burned.

 

The replacement spun freely by hand.

 

I want to make sure I don't burn up a new compressor and waste $200.

 

Any thoughts?

 

Thanks

 

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Did you add the compressor oil? Not freon

No, I did not add oil.

 

How would have have added oil?

 

Oil or no oil..........45 seconds to lock.....it was used, not new, I assumed it already had oil running through it.

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45 secs to lock seems real short...  Maybe there was something wrong with the unit before hand?  I've never run a unit for a/c, mine have always been for OBA.  But my quickest to seize was airing up three 35" tires before it locked up, which was quite a few minutes. 

A Quick and easy check is to pull the unit out, and remove the cylinder head (the back of the compressor), just be careful not to dmaage the gasket.  Then you will be ale to see the pistons and cylinders and be able to see if there was oil in the system and which piston locked up. 
These units run oil in the crankcase and in the freon, which is shared during the operation.  Maybe the crankcase oil had drained out while sitting, and it wasn't added fast enough during the freon fillup (assuming the freon had oil in it) that it heated up and seized.

 

HTH

Ryan

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Just thought I would post this for future reference for anyone who stumbled upon this thread

 

COMANCHE                   Refrigerant Type      Ounces            Oil Type  Ounces
1990-1992  All Engines              R12                  38.00             Mineral     4.50

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Did you add the compressor oil? Not freon

No, I did not add oil.

 

How would have have added oil?

 

Oil or no oil..........45 seconds to lock.....it was used, not new, I assumed it already had oil running through it.

I took a class a few years ago....the instructor was a 30year a/c mechanic and he's always said either new/used compressor there's always an amount of PAG oil to put inside to lube up the pistons so the compressor won't seize up....

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Thanks guys.

 

After I posted this thread, I read my than I ever wanted to know about AC systems.

 

I ordered a new compressor, expansion valve, and accumulator.

 

I will flush the system before installing new parts. A local shop quoted me $20 labor to vacuum down and recharge if I bring the freon........can't beat that.

 

The order is supposed to be here tomorrow.......I report back when I get it done.

 

I won't forget about the oil this time.

 

 

And oh....yeah.......I took one of the old compressors apart, very interesting. The one that was in my truck was bone dry of oil, no wonder it knocked. The one the is now in my truck, the one that locked up, I suspect was bad from the beginning. I don't think I would ever was my time with a PnP compressor, as this one was.

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From the picture - you are sticking with R12, not converting it over to R134a? Since you said you'd bring the freon, was wondering where you got the R12?

 

Or maybe it's been converted over to R134a and the low side valve just looks like the old style. Just curious.

 

Sucks about the oil, there's a plug on top of the compressor that you probably found after the fact. If you replace all those components, you can add oil to the dryer and the compressor before charging.

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From the picture - you are sticking with R12, not converting it over to R134a? Since you said you'd bring the freon, was wondering where you got the R12?

 

Or maybe it's been converted over to R134a and the low side valve just looks like the old style. Just curious.

 

Sucks about the oil, there's a plug on top of the compressor that you probably found after the fact. If you replace all those components, you can add oil to the dryer and the compressor before charging.

I just pulled the new components out of the box. Compressor is labeled 134a.

 

Tell me about the valve??????

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The Factory R12 high/low side ports (I know also called them valves) are very similar to a tire valve typically also called Schrader valves. They are capped in your picture to keep clean and also help prevent slow leaks.

 

When you convert to R134a the ports are more like quick disconnects and the low side (blue) is smaller than the high pressure side (red). They make R134a conversion kits that includes the new ports and screw onto the existing R12 ports on the compressor.

 

The two systems are not compatible, you can't fill or mix R12 with R134a. Here's a Comanche compressor that's been converted to R134a.

 

raqahy6e.jpg

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  • 2 weeks later...

I received most of my parts also. Where are you at on this Jeep Driver. I was pulling the old off today and noticed I have to but one line. I am ordering it tonight.

 

Also Zach posted 4.5oz of mineral oil. I see that is for R12. Would it be the same for Ester or Pag. Does anyone know wich Pag oil to use? It comes in three viscosities.

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