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Compressor Selection

Roadkill_Gaming
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Roadkill_Gaming New Member

Roadkill_Gaming

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The AC in my 2018 LTZ went out. I hooked up a manifold gauge set and put the system under 30inHg of vacuum. Over the course of two hours it dropped to about 27inHg. It makes me think a seal on the compressor is bad. I am going to throw some 1234yf (as called for by info panel on fan cowling) that is dyed to verify.

When researching replacement compressors, I found GM Genuine 85656961; This is what GM Genuine's website reccomends based on my VIN. RockAuto lists that part number under GM Genuine 86798574, which does not exist on the GM Genuine site.

The listing on RockAuto says that it is R134a. My truck has the 1234yf sticker. I know MY2017/2018 was the transition years for 134a to 1234yf Are the two compressors compatible? I know that 134a and 1234yf do not mix and use different fittings.

Any help is appreciated.

Rock Auto listing https://www.rockauto.com/en/moreinfo.php?pk=14080089&cc=3437551&pt=6628&jsn=1000

GM Genuine https://parts.gmparts.com/product/gm-genuine-parts-air-conditioning-compressor-kit-85656961

newdude Senior Enthusiast

newdude

Posted
Posted
21 minutes ago, Roadkill_Gaming said:

The AC in my 2018 LTZ went out. I hooked up a manifold gauge set and put the system under 30inHg of vacuum. Over the course of two hours it dropped to about 27inHg. It makes me think a seal on the compressor is bad. I am going to throw some 1234yf (as called for by info panel on fan cowling) that is dyed to verify.

When researching replacement compressors, I found GM Genuine 85656961; This is what GM Genuine's website reccomends based on my VIN. RockAuto lists that part number under GM Genuine 86798574, which does not exist on the GM Genuine site.

The listing on RockAuto says that it is R134a. My truck has the 1234yf sticker. I know MY2017/2018 was the transition years for 134a to 1234yf Are the two compressors compatible? I know that 134a and 1234yf do not mix and use different fittings.

Any help is appreciated.

Rock Auto listing https://www.rockauto.com/en/moreinfo.php?pk=14080089&cc=3437551&pt=6628&jsn=1000

GM Genuine https://parts.gmparts.com/product/gm-genuine-parts-air-conditioning-compressor-kit-85656961

 

 

85656961 and 86798574 are both correct.  85656961 is the current number, 86798574 is the previous number, so Rock Auto probably has some older stock is all.

 

Compressor services 2015-2018 so the type of freon won't matter.  Fits trucks that had either R134a or R1234yf.  

 

Be careful just adding in freon.  You don't want to be in a position of it being overfilled.  The ideal thing would be to have a shop suck it down and recharge it with dye to the proper amount, then look for leaks.  

 

My gut says your condenser is bad, which they always are on these 14-19 trucks.  Could also be one of the two hoses connecting to the compressor. 

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Roadkill_Gaming New Member

Roadkill_Gaming

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47 minutes ago, newdude said:

 

 

85656961 and 86798574 are both correct.  85656961 is the current number, 86798574 is the previous number, so Rock Auto probably has some older stock is all.

 

Compressor services 2015-2018 so the type of freon won't matter.  Fits trucks that had either R134a or R1234yf.  

 

Be careful just adding in freon.  You don't want to be in a position of it being overfilled.  The ideal thing would be to have a shop suck it down and recharge it with dye to the proper amount, then look for leaks.  

 

My gut says your condenser is bad, which they always are on these 14-19 trucks.  Could also be one of the two hoses connecting to the compressor. 

Hmm, I will check out the condenser as well. When I hooked up my gauges I had 0 psi on high and low side, and never smelt any Freon during the vacuuming down. My diagnostic tool was reading 5psi on the high side when it was around 80deg out. I'm pretty sure I had nothing in the lines to recover.

Before I buy any parts, I am going to charge with 1 can of 1234yf-uv (8oz) to find the leak for sure.

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