A/C Compressor Troubleshooting

[sahls01gmc]

I have an '01 Sierra 2500 (non HD) with 250,000 miles on it. The A/C compressor froze a while back, and I wanted to know what what typically needs to be replaced. It malfunctioned because it "froze" which caused the belt to shred. Do you think the compressor itself is locked up, or is there a possibility that just the bearing needs to be replaced?

 

The system has been evacuated already, so I just need to know what I should look for once I get the compressor off of the engine.

 

 

Thanks for any suggestions! Let me know if you need to know more details.

[Doug_Scott]

Does the pulley that the belt runs on spin freely? At the very front edge of the pulley is a plate. That plate is connected to the crankshaft in the compressor. Normally the belt portion of the compressor spins freely until the plate on the front of the compressor gets activated and starts being driven by the belt. Does the front plate turn by hand with the engine off and key out of the ignition? If the belt part does not turn, then the bearing for the belt part is seized. If the belt part turns freely, but the front plate does not, then the compressor is seized. Once you know which part is broken, you will know what you need to change.

[grampadirt]

I would think with a compressor with that many miles on it you'd be wise to replace it.However,most mfg'rs won't warranty the compressor unless you replace the dryer & orifice tube or expansion valve also.

[grampadirt]

I would think with a compressor with that many miles on it you'd be wise to replace it.However,most mfg'rs won't warranty the compressor unless you replace the dryer & orifice tube or expansion valve also.

 

Dbl. post,sorry.

[sahls01gmc]

Thanks for the fast replies!

 

As of right now (with the compressor still on the engine, and no belt on it) the pulley does not spin freely. I'm inclined to think the bearing is froze, but there is also a reason why I am not a ceritified mechanic.

 

grampadirt, That is exactly why I am trying to figure out the best option. I don't really want to replace all of the rest of the equipment just for the warranty, but I guess I gotta do what I gotta do.

 

I'll know more once I get the compressor off, which should be tonight. Unless my kids have other ideas for me tonight....

 

 

Thanks again guys!

[grampadirt]

I just had to replace those parts on wifey's suburban.I sprayed a soap/water solution on the old compressor and noticed a few air bubbles coming out from where the compressor is pressed together,so I figured it's a '99,time to replace some parts.

[sahls01gmc]

Yeah, and when I had the A/C evacuated, I only had .09lbs of refrigerant left in the system. So I am guessing there is a leak somewhere, so I might have to replace the whole systme by the time I get done with it!

[grampadirt]

When it's all said and done you'll have nice cold A/C

[gmtech4]

ya dont have to replace the whole system ,lord thunderin ,,,take it to a shop to finish the job ,they will install oil and all that ,have them replace the filter thingy lol and fill it up with the right stuff ,,,,,,dont take off the compressor ,you will induce crap to the system,

 

just let a shop do it

[txab]

Filter thingy?

[gmtech4]

ya ,the name is not in my head ,orfice tube ,there,thats it !!!!

 

make sure they change the ORFICE TUBE !!!!

 

lmao ,,,,i knew someone would see that lol

[sahls01gmc]

Here's the update. I have taken the compressor off (I know you said not to govtech4, but I'm fairly certain something could potentially already be in the system seeing as it only had .09lbs of refridgerant when I had it evacuated), and found that the pulley spins rather freely, and the front plate does not spin as freely. Although it still moves, am I correct in believing that the compressor has seen it's last days? Also, I would assume that I have to replace the seals where the lines go into the compressor, right?

 

Any other thoughts or suggestions are more than welcome!

 

Thanks for your help.

[gmtech4]

seals come with new compressor ..

[sahls01gmc]

What should the normal tension be for turning the compressor by hand? The pulley can spin freely almost 6 or 7 turns before stopping. I can rotate the front plate by hand, and can hear the compressor "pumping". It feels similar tension to rotating a bowling ball across a table (sorry, only analogy I could come up with right now). If I cover up one hole with my hand, I can feel it trying to blow out. And vice versa when I cover the other hole.

 

I'm starting to think that the compressor is ok, I can't see any signs that tell me that it doesn't work properly.

[Doug_Scott]

What should the normal tension be for turning the compressor by hand? The pulley can spin freely almost 6 or 7 turns before stopping. I can rotate the front plate by hand, and can hear the compressor "pumping". It feels similar tension to rotating a bowling ball across a table (sorry, only analogy I could come up with right now). If I cover up one hole with my hand, I can feel it trying to blow out. And vice versa when I cover the other hole.

 

I'm starting to think that the compressor is ok, I can't see any signs that tell me that it doesn't work properly.

 

The compressor is just that, a compressor. One port is intake, other port is exhaust. Pulley should spin freely, and quietly.

If the system still had some refrigerant in it, then that also means there was still some pressure in the system. That also means moisture or contaminants could not get into the system due to more pressure inside than outside. Since you took it apart before finding the leak, you will have to now re-install everything, put a charge into it, and check for leak and repair it. By opening the system you have allowed the receiver dryer to become contaminated. At the very least now you need to replace receiver/drier, fixed orifice tube, "O" rings for compressor, and then have the system put under a vacuum (to remove moisture by lowering boiling point to room temp), add oil and recharge system.

You may want to check prices on a rebuilt compressor to see if it is worth re-using the original compressor. Sometimes changing the front pulley bearing and front shaft seal kit costs about as much as getting a rebuilt compressor.