# Bad A/C Compressor?



## snowwy66 (Nov 5, 2017)

It's recommended to change the receiver dryer anytime a part is changed. More with the compressor though. It's a filtration sort of like thing in the system. For contaminants and moisture. 

If you know your ac is spinning and you're not getting cold air. It's either low on freon or something is wrong. It only takes 50 pounds of pressure to kick the compressor on. A fully charged system with compressor off will sit at around 110 pounds. Give or take a few pounds. 

So, just because you see the compressor spinning. Doesn't mean it has enough freon to blow cold. 

My 17 cruze bought new 9 months ago only came with 60% charge. It wasn't anywhere near cold that it is now. With a full charge.


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## Robby (Mar 1, 2013)

Over the years I have replaced quite a few compressors that either failed internally or were just worn out.
The clue was always weird pressure readings.....high side (output) way too low alongside a suction (low side) much too high.

Yes, when a compressor is replaced there are several other components (drier, orifice tube, flush solvent to clean out condenser and evaporator, etcetera). Generally when a compressor dies it shoots bits of aluminum throughout the system.....hence the part replacement after the flushing procedure.......just the correct way to perform the repair for a long system life.

So far, assuming the diagnostic is correct, the procedure you describe is correct.

Rob


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## jblackburn (Apr 14, 2012)

I had the expansion valve die on my Gen 1 at a fairly early age. It showed VERY high high-side pressures, then the AC compressor would kick off entirely, scream the fan, then kick back on.


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## Drewie64 (Nov 26, 2017)

Yup, the guys I brought it to pulled a vacuum on the system and replaced the refrigerant but the high side was not even registering 100 PSI. Only after they replaced the cooling fan did the pressures start behaving erratically.

I was quoted at $1,775 to replace the A/C compressor, the condenser, and expansion valve. No I did not mistype that, $1,775. Does this seem accurate? $1,000 for parts and $600 in labor. The rest is taxes and "Environmental fees"


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## Taxman (Aug 10, 2017)

I assume the labor charge is just flat rate hours x their hourly rate.

I see about $500 in factory parts at favorable prices (plus o-rings refrigerant etc).
Maybe $100 less if you just replace the drier instead of the whole condenser assembly. 
A dealer probably won't let you bring your own parts, an A/C shop won't guarantee the parts you bring in. 

Some dealers sell below MSRP at the parts counter, one forum member rebuilt a wrecked car and his local dealership charged him less than the online dealers, but that might have involved a quantity discount because he ordered a lot of parts at once. 


https://www.gmoutletparts.com/oem-parts/gm-condenser-23305638

https://www.gmoutletparts.com/oem-parts/gm-compressor-13414019

https://www.gmoutletparts.com/oem-parts/gm-expansion-valve-13313727


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## snowwy66 (Nov 5, 2017)

@*Taxman* 

I suggest you read the book and stay away from google and youtube. 

Subcooling

That word isn't even used in the book. Nor was it on the test I took to buy freon. And nobody recalls it being mentioned in the first book we had to read to buy freon 26 years ago either. 

FYI


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## Taxman (Aug 10, 2017)

snowwy66 said:


> @*Taxman*
> 
> I suggest you read the book and stay away from google and youtube.
> 
> ...


I suggest you pull your head out of the 20th century and quit claiming your ignorance of modern industry standard service methods is wisdom.

EDIT: On second though, that sounds too harsh. You called me out by name so I threw it back at you, but it doesn't help anybody who's wasting their time reading it. 

In automotive systems (and ductless mini splits), all the parts are known to the designing engineers, so they specify a charge weight. The technician evacuates the system and puts the prescribed number of ounces back in. Quick, easy and accurate. 

In building HVAC, parts are more mix and match, so if they want to get it right, they set the metering device by superheat, and they set the charge weight by subcool. If you want to substitute your judgment for that of the engineers who designed it, take this route, if you're just following a number on the red pressure gauge you're flying mostly blind. 

Overcharging just adds head pressure and power consumption without doing much for performance.


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## jblackburn (Apr 14, 2012)

Taxman said:


> I assume the labor charge is just flat rate hours x their hourly rate.
> 
> I see about $500 in factory parts at favorable prices (plus o-rings refrigerant etc).
> Maybe $100 less if you just replace the drier instead of the whole condenser assembly.
> ...


I had a dealer match GM Parts Direct online prices. Worth asking at the least; if you intend to get the work done there, you may save a bit.



> In automotive systems (and ductless mini splits), all the parts are known to the designing engineers, so they specify a charge weight. The technician evacuates the system and puts the prescribed number of ounces back in. Quick, easy and accurate.



This is the correct way, especially with today's variable displacement AC systems.


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## snowwy66 (Nov 5, 2017)

Taxman said:


> I suggest you pull your head out of the 20th century and quit claiming your ignorance of modern industry standard service methods is wisdom.
> 
> EDIT: On second though, that sounds too harsh. You called me out by name so I threw it back at you, but it doesn't help anybody who's wasting their time reading it.
> 
> ...


I suggest you get some experience. 

Going blind. THAT'S FUNNY. 

Those recharge kits on the shelves are going blind. 

But I'll let you in on a little secret. 

The new 21st century way puts a car at 250 - 275.

The sweet spot always comes in at 225. ALWAYS. 

Last i checked. 225 was lower then 250 - 275. 

Since you can't do the math. 300 would be overcharged. 225 is undercharged.

Get yourself some gauges and a meat thermometer. You'll quickly learn. 

The coldest point. Would be undercharged.

The gen2's call for 18.145 oz. That's 255. The sweet spot is 17 oz. That's 225. And THAT my friend. Was done the 21st century way.

You see. I can do that. Cuz i have ALL the equipment. 
Full analog and digital gauges with a databank that contains capacities for 55 makes and models. Should the car NOT have the decal it was shipped with. 30 lb cylinders of freon. A freon weight scale. Vacuum pump. Thermometer. And access to a recovery machine anytime i want.

Overcharge has never happened. And it's unlikely to happen in the future.


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## jblackburn (Apr 14, 2012)

Stop it or I will start deleting things. The OP just asked for help diagnosing what's going on, not an argument on his post.


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## gwsmallwood (Jun 25, 2018)

For reference, a mechanic I trust just replaced my compressor. It wasn't gone yet, but it was leaking and on it's way out, so we decided to do it now so I wouldn't need the condenser, drier, etc. replaced too. Labor was just under $500 for around 4.5 hours of work, parts (including coolant and shop supplies) was around $600. Evidently the GM Compressors are around $500 no matter what sort of discount you have. My mechanic is a friend of the family, so he gave me a discounted labor rate that brought my total down a few hundred from there.


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## subjectpush (Jun 4, 2018)

So GMPP plan won't be covered this issue? Sorry, I am new to the car's world!


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## jblackburn (Apr 14, 2012)

subjectpush said:


> So GMPP plan won't be covered this issue? Sorry, I am new to the car's world!


GMPP plan should cover it 

Sent from my SM-G950U using Tapatalk


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