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Need Help solving a Mystery Comp. Fail.

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AirServiceCo

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I need help solving a Mystery about a Compressor failure. A friend who owns another small AC Co. asked me to Change out a Comp. on a 5 Ton, Trane Rooftop Unit. I replaced it and it ran for about a week when he called and said it wasn't working. I went back out and checked it out. I couldn't get into the building so I went on the roof and saw it running. First I felt the Heat coming off the cond. fan and it was Hot. Then I felt the Suction pipe and it was cold and sweating. I looked over at the drain and could see water draining onto the roof. By eye everything looked good. I put my gages on and the pressures seemed high. I couldn't get into the space because it was locked.... I adjusted the pressures (-1.5lb.) without checking superheat and left. The next day my friend sent me a pic of the Frozen E-Coil. He said he had to add 5lb R-22 and left it running at a 10deg superheat. About 2 days later (total aprox. 2 weeks) the Comp. fails. He calls me and says that the Comp. was wired wrong and now he has no pressures. I went out to confirm and ohmed the Comp. windings. They had perfect ratio and no windings burnt. Comp. tried to start by dropped out quickly. I got a start kit hoping that Thermal wasn't still open. It wasn't and needed 120amps to start...then dropped to about 23 amps and continued. Still no pressures. Is it possible that I wired the Comp. wrong? Note: My friend is one of the best AC Techs I know... he doesn't miss much. I think I'm getting a bad rap. LOL Is it possible for a 220, 1ph, R-22, Trane Comp. to run with CSR wires wrong? Is it possible that 2 Techs with 20+ years of experience to both miss it?
 
#2 ·
Anything is possible right? I would have said "hey you sent a pic of the frozen coil where is the proof I miswired it "

Because I know after you replaced the compressor you checked the amp draw on c r s and compared to data plate and also check c + r together and compare that amp draw to S right?

Trust me I know after a long job like that some stuff can get overlooked but always try and cycle the new compressor and try and see if you can find what killed it.

Also don't buy into the myth that hard starts are for dying compressors. A high quality 5-2-1 is a good upgrade for any compressor.
 
#3 ·
Kinda hard to give any good advice without all the information... You said pressures were kinda high, exactly how high? Superheat before and after you removed refrigerant, Subcooling, Fixed orifice or TXV, Drier good? Did you weigh in Nameplate after compressor change out? Comp Name Plate Amps would be good too. Current Ambient Conditions. But it sounds like a mechanical failure to me just from the information you gave. Was the old compressor electrical or mechanical failure?
 
#4 ·
It sounds like you've had trouble with the charge. High pressures then freezing and what not. But for him to say you wired it wrong and now it won't compress after he reworked sounds like he wired it wrong. Maybe switched run and common? Usually when it mechanically fails it won't compress but with draw little amps. It's possible it's failed mechanically but that's fast for a new compressor. I'd double check my wiring. Check charge for sure. 10 degrees of superheat is over charged. 15-18. Is it a txv? Piston?
 
#5 ·
AirServiceCo said:
I need help solving a Mystery about a Compressor failure. A friend who owns another small AC Co. asked me to Change out a Comp. on a 5 Ton, Trane Rooftop Unit. I replaced it and it ran for about a week when he called and said it wasn't working. I went back out and checked it out. I couldn't get into the building so I went on the roof and saw it running. First I felt the Heat coming off the cond. fan and it was Hot. Then I felt the Suction pipe and it was cold and sweating. I looked over at the drain and could see water draining onto the roof. By eye everything looked good. I put my gages on and the pressures seemed high. I couldn't get into the space because it was locked.... I adjusted the pressures (-1.5lb.) without checking superheat and left. The next day my friend sent me a pic of the Frozen E-Coil. He said he had to add 5lb R-22 and left it running at a 10deg superheat. About 2 days later (total aprox. 2 weeks) the Comp. fails. He calls me and says that the Comp. was wired wrong and now he has no pressures. I went out to confirm and ohmed the Comp. windings. They had perfect ratio and no windings burnt. Comp. tried to start by dropped out quickly. I got a start kit hoping that Thermal wasn't still open. It wasn't and needed 120amps to start...then dropped to about 23 amps and continued. Still no pressures. Is it possible that I wired the Comp. wrong? Note: My friend is one of the best AC Techs I know... he doesn't miss much. I think I'm getting a bad rap. LOL Is it possible for a 220, 1ph, R-22, Trane Comp. to run with CSR wires wrong?
Click to expand...
Well, it would not last a week!

When you visited the rooftop, the hot discharge tells you that it is transferring heat & must be producing near-correct power. The cold suction line says that SH is roughy ball park. That & the condensate discharge means that it is not froze up therefore not terribly low on charge.

Without further info we're into speculation, eg: your friend grossly overcharged it (add 5lb???) to the point that the returning liquid took out the valves, "no pressure, he cried", and 2 days running with liquid floodback could wash out the bearings (hard start). Just a thought. He's the best tech you know? Maybe he's jerking your chain. Maybe you need a new friend??
 
#8 ·
Tommyz23 said:
Could liquid locked. Remove some refrigerant. Won't compress If grossly over charged.
Click to expand...
Good thinking. But after hard start, why NO pressure (& no mention of internal relief howl). FLA is ballpark, that's why I threw in washed out bearings.
Like Cap says, 5 lbs should be near-listed chge. Did OP leave cap off a leaking access valve?

Definitely still open to discussion.
 
#9 ·
IRBH said:
Good thinking. But after hard start, why NO pressure (& no mention of internal relief howl). FLA is ballpark, that's why I threw in washed out bearings.
Like Cap says, 5 lbs should be near-listed chge. Did OP leave cap off a leaking access valve?

Definitely still open to discussion.
Click to expand...
Hardstart or not it won't compress if its grossly over charge. He got it running. If its running its past starting. It can't overcome the liquid. But if his friend wired and its running backwards, it won't compress either.
 
#11 ·
Depending upon the exact model, a 5 ton Trane Rooftop unit holds at least 10 pounds of R-22.

It appears that the compressor is toast. Now all you can do is replace it with the usual steps, plus I would suggest: document wiring connections, refrigerant charge weight, pressures and superheat values with pictures. Let us know how you resolve this dilemma.
 
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#13 ·
If the single phase compressor is wired wrong it will not start. Depending how it was wired wrong it could burn the windings and there you go You have a dead compressor.
You need to verify how the compressor is wired now.

Jlang
 
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#16 ·
AirServiceCo said:
Thanks guys. I do believe ya'll have solved the mystery. Not Happy about it though. I would have rather have wired it up wrong than lose a friend. Thanks
Click to expand...
Everyone has their flaws.
Sit down with him, lay out the facts (these posts should help) and explain that it's impossible to attribute the failure on your hookup & that you're not accepting the blame!
Then keep your guard up when dealing with this friend in the future.
 
#17 ·
Quote Originally Posted by timjimbob View Post
Recip compresses wired backwards will pump. ......
Shake the 3ph out of yr head... this is a single ph compressor!

BUT a missed wired single phase compressor will run backwards
 
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timjimbob
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