Destroyed multiple AC compressors

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Old 07-29-17, 12:24 AM
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Destroyed multiple AC compressors

Have an '07 Dodge dually diesel that was hit so hard in the front, it pushed the engine back a foot, through the firewall. I helped a friend rebuild it in 2010 in his body shop, to include a new AC compressor and entire heater box. After the rebuild, the AC worked fine for over four years. then the AC compressor clutch burned up. He threw on a new compressor, and that worked fine for another two years. Don't know if the compressor locked up or not. All he knew was it wasn't pumping.

Today it's two years later and the clutch is burned up again. He put on another new compressor, and that worked great for all of about five minutes. Got it replaced under warranty, and that one only worked for 30 minutes, then I arrived to save the day!

What he didn't realize was the clutch was slipping and the new compressor was locked up. We assume the first new one did too, but it has been returned already. I took the old one apart and found the wobble plate very badly chewed up, and the pistons were jammed. Also found a real lot of metal powder in it, and no sign of oil. He claims he added 7 ounces of PAG oil before installing it. Even if he forgot, it wouldn't explain three recent failures. He has fairly new refrigerant recovery and charging equipment, and knows how to use it, so his competency is not the issue, . . . I think.

With the first new compressor today, he also replaced the pipe with the orifice tube, and the accumulator. After this current compressor was found locked up, we found air can only be blown through the condenser one way, and not very easily. It appears to be plugged with debris and is going to be replaced. This truck belongs to a friend of his who is also a good customer. At this point he is talking about ordering a complete kit to include a new compressor, condenser, evaporator, accumulator, and all the hoses. The frustrating part is the time he is going to spend pulling the heater box / dash apart to change the evaporator. My concern is we don't know why there have been so many compressor failures. He specializes in rebuilding one and two-year-old smashed Dodge trucks. He has a frame rack, paint booth, and all the latest equipment, so he isn't exactly a do-it-yourselfer. One of my specialty areas is electrical, but I know more AC theory than I have experience with it. Neither of us have seen this before, and while replacing every refrigerant part should solve the problem, I'm looking for advice I can share with him as to what caused these failures, and if the repair approach is practical. Neither of us are comfortable trying to flush the evaporator or leaving on a part that might contain debris.

Where did the oil go that was in the compressor? This was the one that was on the truck for the last two years. There was barely even a light film of oil on the shaft.

Thanks bunches;
carradiodoc
 
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Old 07-29-17, 04:21 AM
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Most times with air conditioning problems are fairly straight forward and not too difficult to resolve.
However, there are times when you need a solid knowledge of basic principles and this appears to be one of them.
A clue in your story is that the plugged condenser would be glaringly obvious if gauges were properly used.

Unfortunately we do not support diy refrigeration work because of certification requirements.
Once the system is put back together you may want to consider paying someone qualified to help you with this.
 
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Old 08-06-17, 11:42 AM
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AC Comp

At any point was the system ever flushed? Sounds like debris locking up comp.
 
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Old 08-08-17, 05:57 PM
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Can you turn the compressor by hand? Did the instructions clearly say to add 7 oz of PAG? Many compressors come pre charged with oil for the whole system. If that's the case, adding another 7 oz could be the cause of the lock up, oil just doesn't compress. When he changed the orifice tube, was there any sign of debris on the screen?

Most lockups I've encountered would slip the belt, if the clutch was slipping, I'd suspect low voltage at the clutch (which is probably why the original clutch failure happened). You need to measure voltage with the clutch engaged by back probing the plug or use test leads with a load button. High resistance in a circuit will show battery voltage when that circuit is open, so checking voltage by unplugging the clutch and checking power and ground at the plug really tells you nothing.

At this point I would flush the entire system. Some evap cores and condensers cannot be flushed and will need to be replaced.
 
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