2020 Silverado 1500 Duramax LM2, AC compressor replacement advice

JhnyRed · September 11

Long story short the dealership has my 2020 Silverado 1500 4x4 with 60k miles, that I took in for the AC not cooling. It worked perfectly, blowing very cold until it didn’t one day. Like the switch wasn’t activating the clutch on the compressor. Anyways it is showing 180lbs on the high pressure side and 120lbs on the low side. Obviously very high on the low side. GM is recommending a $958 replacement of the expansion valve first and then if that doesn’t work then $2800 to replace the compressor!! The mechanic thinks it’s the compressor and I tend to agree begrudgingly. I hate to blow $1000 on a 50/50 chance and then have to replace the compressor anyways. I have a couple of questions below.

1. Any ideas one way or the other on the diagnosis? The electrical all tests out and the compressor is running.

2. If the compressor needs to be replaced what are the issues I would run into doing it myself? Not the recovery or the charge as I have a good friend that can take care of that. I’m mainly talking what has to be removed to get to it and get it out? The truck has a 6” lift and I was thinking removing the wheel and inner fender to access it from the side. I don’t have the truck to even look at it so I’m not sure what that area of the compartment looks like. I’ve done plenty of mechanical at this level but I don’t want to damage it. She’s a beautiful truck that mainly just gets used to tow my boat or a 14’ enclosed trailer so she’s mainly a garage queen.

Edited September 11 by JhnyRed
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silveradosid · September 20

if you friend can evacuate the system, i would do the expansion valve yourself. it only takes about 20 minutes to change with the system empty. 958 to change it is just criminal for a 1 hour job

JhnyRed · September 24

We’ll long story short. With no information anywhere that I could find on changing the compressor and not being able to even see it on the truck with all the stuff in that part of the engine compartment, I negotiated with the dealer. I didn’t feel it was the valve, but it sure seemed like the compressor was toast. That said with some doubt I didn’t want to ruin a new compressor if there was a chance the valve was the culprit. I offered just pay $3000 to do the compressor and expansion valve at the same time. That would be about $800 less and we won’t know if the valve was the cause. The service manager came back with a counter offer. They would replace the valve first per GM’s recommendation. If that repaired it then I would just pay the $958. If not they would do the compressor for a total of $3200. It put some risk on them and a possibility of only paying for the valve for me. I really didn’t have any other options in my area so I said do it. Sure enough the valve replacement didn’t do anything so they replaced the compressor. Not a happy ending financially but it’s a bad design of where the compressor is in the truck. With the $188 hr labor rate it’s brutal for just a compressor. The service writer was a good guy and I at least got them down $600 and there was the possibility it could have been under a grand. Oh well. I figured I would at least share my experience for the next guy. It’s all fixed and it’s cool in my cab again!

Shall36 · September 26

Don’t feel all too bad. If the compressor had internal damage and was pushing bits through the system, changing the expansion valve along with the compressor makes very good sense. Of course, I am assuming they also did the accumulator while they had the system open, and hopefully they also flushed the rest of the system to get any trash out.