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Compressor gone or not?

OldTimer6789 on Wed July 10, 2013 9:04 PM User is offline

Year: 1972
Make: Chevy
Model: Chevelle
Engine Size: 496
Refrigerant Type: R-134a
Ambient Temp: 100+
Country of Origin: United States

Nubi here,
Sorry if this is a long post.

I finally collected all the parts to get my A/C back in service. I decided to convert to R-134a. Here is a list of what was purchased:

1) Evaporator and Condenser flushed
2) New Dryer
3) New Expansion valve
4) Rebuilt Compressor with proper oil (for R-134a)
5) Rebuilt POA valve (for R-134a)
6) New hoses/)-rings

After parts installed, list of what was done:
1) Evacuated system to -24 Inches Hg for 45 minutes
2) Verified no leaks in system
3) Charged in 36 oz. R-134a
4) Bypassed Thermal Switch on compressor

Pressures in PSI were 40 low side and 200 high side and vent temperature was down to 50 degrees when compressor started seizing. Shut down immediately and waited until the next day to retest. Only ran A/C for about 10 minutes before compressor started seizing again. My initial suspension is that I might have gotten some liquid freon in system, though I did not see any going in on gauge manifold.

My questions are:
1) Do you believe compressor is toast?
2) Should I evacuate the system again, change out the dryer and recharge?
3) Should I flush the system, evacuate, change dryer, and recharge?

Thanks for your help,

fix_it on Wed July 10, 2013 10:11 PM User is offline

This is an A6 compressor, correct? Where did you add the oil? The A6 has an oil sump and must be filled through the crankcase drain bolt hole. If you just added it to the lines, or distributed it through the components, the oil probably did not reach the compressor before it was damaged. And to answer your question, if the compressor did really seize, then I'd say yes it's gone. Even if it still turns. Now you probably have metal in the system and need to flush it and start over.

Just curious, what brand compressor did you use? Some are know to be questionable. Also, from my experience with the same system on a 69 Cutlass about 15 years ago, you probably need at least an electric fan, and maybe a better condenser if you want performance equivalent to R12. Maybe not, but mine always ran warm with high head pressure.

OldTimer6789 on Thu July 11, 2013 7:42 PM User is offline

Yes, it is an A6 compressor from Classic Air. It was shipped with oil already. Compressor shaft was turned as per instructions to remove oil from cylinders. I'm pretty sure I can't return for warranty, but I will give them a call.
I'm thinking of getting another replacement compressor from Autozone, but they say for R-12. I'm not sure if they come with the oil already. If not, I should be able to put in the proper R-134A oil and try that out.
It's really frustrating to be so close to having A/C after 6 years and then having this happen.

Olds442 on Thu July 11, 2013 11:59 PM User is offline

Not staying with R-12 was your first mistake.

iceman2555 on Fri July 12, 2013 9:34 AM User is offlineView users profile

It appears that this repair was well though out and executed.

Since the compressor will operate for several minutes and then begin to 'freeze' it appears that this maybe a potential pressure type problem. Liquid refrigerant would probably not result in a compressor lock up under the expressed conditions. It is doubtful that it would ingest a sufficient amount to result in total freeze up. If this is a situation when the compressor freezes...releases... and repeats this process, yes, this could be a liquid ingestion problem.
What type flush was utilized for this repair? Was the lubricant shipped with the compressor drained and the correct type and amount added back to the unit or was it simply installed as shipped? Question would be what type lube was shipped with the unit and the volume of lubricant. Never been trusting of labels stating that the compressor contained the necessary lube for a unit. Most A6's are shipped with mineral lube, this is because this compressor was never designed to operate with 134a. That being said...they will 'pump' 134a but the refrigerant tends to present several issues after a retro fit. Esp with leaks around the shaft seal.
Start the vehicle, engage the clutch and test for a possible restriction. This can be accomplished utilizing temperatures and using your fingers. Begin at the discharge side of the compressor and simply touch the should be hot....uncomfortable to maintain contact....but not excessively follow the flow and test the liquid line (before the rec/drier) in the same manner. Test the rec/drier the same manner....temps should be approximately the same temp. If the temp change is here is drastic...this could be a flow issue with the rec/drier.
The 'calibrated' POA valve could be an issue...this would or could result in the liquid charge condition....although the 50 degrees vent does not represent a possible flooded evap which could result in a ejection of liquid refrigerant from the evap.
Monitor the discharge line temp closely...esp about the time of 'lock up'...if this line becomes excessively hot at this time....this could be the issue.
The indicated pressures for a retro fit are seriously low for the stated ambient temps....expected high side pressures would be in the 275 or higher at 100 degrees. Although this vehicle does have a large exposed condenser face....200 PSI would be considered to be below expectations.
Although a A6 has a sump....they can be 'pumped' dry. Insure that there is lubricant in the compressor sump. Contact the comp supplier to determine the type/amount of lubricant installed in their units. Still do not trust this info...a suggestion would be to remove....drain completely and re install. It is doubtful that the operational time would result in a 'dry' could be a lubricant flow issue.
The A6 has a oil pump in the rear head and this should maintain lubricant flow. Insure that the compressor does have lubricant.
A conversion back to 12 would be the best step...but the retro can be accomplished and will provide adequate cooling. Have worked with a client located in Jax FL for a period of time that had a Lincoln retro fitted and he has had serious problems with his retro. The system continuously looses refrigerant at the shaft seal and he has decided not to make the change to a newer GM seal. States the cost fact is too great...and he simply wishes to continue to add refrigerant.....his decision. He did remove the POA and installed a POA eliminator kit.....not a good choice either (my opinion) but it is his vehicle.
R12 vehicles were never envisioned to operate with an refrigerant other than R12 and many simply perform better with 12. Yours is one that should remain with 12 as is the Lincoln. Once more this is simply an opinion.

The strongest reason for the people to retain the right to keep and bear arms is, as a last resort, to protect themselves against tyranny in government.
Thomas Jefferson

OldTimer6789 on Fri July 19, 2013 9:56 PM User is offline

Finally got a day off!!

OK, So all of the parts were purchased from Classic Auto Air and ordered for the R-134A conversion. A/C compressor was stated to be filled with proper oil for R-134a at proper level. They actually told me the type oil and amount, but I forgot to write it down. I did remember that I was supposed to charge from 43 to 48 oz., which I only had 36 oz. in when my troubles started.
The flush of evaporator and condenser were done using a flush called A/C Pro, which said was a solvent based flush compatible with both R-12 and R-134a. This was done several times using an air compressor to completely push through. After all liquid blown out of evaporator and condenser, all parts were sealed back up until all parts were installed. Hoses hooked up lastly before evacuation was done.
I will try again this weekend to run while checking for a restriction or pluggage problem. I will purchase a laser temp. gauge to test. Hopefully, I will see something, though I'm not comfortable running it until it seizes again. I do recall seeing some oil in the high-side gauge hose when I disconnected. Could this be a problem?

Thanks for all the help.

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