Recently, while checking a 3-ton r-22 Tecumseh hermetic compressor, I found that there was no refrigerant left in the unit, the terminal cover was not in place but lying around, oil was spilled all over, and that one of the terminals had blown off. Neither the terminals nor the wiring connectors or the point where the terminal comes out of the compressor body were scorched, so I can eliminate a poor contact condition. I sawed off the top of the compressor and found out that the coils were OK. So, what happened here ??? what caused ther terminal to fly away ?
compressor terminal blow-off
rackrookie
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Recently, while checking a 3-ton r-22 Tecumseh hermetic compressor, I found that there was no refrigerant left in the unit, the terminal cover was not in place but lying around, oil was spilled all over, and that one of the terminals had blown off. Neither the terminals nor the wiring connectors or the point where the terminal comes out of the compressor body were scorched, so I can eliminate a poor contact condition. I sawed off the top of the compressor and found out that the coils were OK. So, what happened here ??? what caused ther terminal to fly away ?
Got a pic?
Sounds like the terminal's mounting mechanically failed.
I wonder what Tecumseh has to say?
jogas
Terminal failure !!!
While rare, this failure will obviously occur. You may never know the exact cause of the failure because a lot of the evidence is now gone. You can't recover the refrigerant to check for the proper charge, you can't run the compressor to test it(the system) for several possible problems. So now what ? Troubleshoot - troubleshoot - troubleshoot - leave no stone unturned once you change out the compressor. Look at the old compressor, what residual oil may still exist, is it burnt, is there copper plating ? If you cut the refrigerant lines rather than debrazing them, are they discolored, does the system have an odor. Is it possible it(the unit) took an electrical hit or surge. How bad was the electrical fault when it failed ? Did it trip only the fuses to the unit, or did it take out a major branch circiut ? Change out the small support components, LPC, HPC, time delay, contactor, if single phase change all start components, you get the idea. The point is, you will have do your best to prevent a reoccurrance of the failure. Once you start the replacement compressor, test all operating paramters. Add any safety components to the system if you observe an abnormally only the tech on site will be able to locate. Good luck !!!
While rare, this failure will obviously occur. You may never know the exact cause of the failure because a lot of the evidence is now gone. You can't recover the refrigerant to check for the proper charge, you can't run the compressor to test it(the system) for several possible problems. So now what ? Troubleshoot - troubleshoot - troubleshoot - leave no stone unturned once you change out the compressor. Look at the old compressor, what residual oil may still exist, is it burnt, is there copper plating ? If you cut the refrigerant lines rather than debrazing them, are they discolored, does the system have an odor. Is it possible it(the unit) took an electrical hit or surge. How bad was the electrical fault when it failed ? Did it trip only the fuses to the unit, or did it take out a major branch circiut ? Change out the small support components, LPC, HPC, time delay, contactor, if single phase change all start components, you get the idea. The point is, you will have do your best to prevent a reoccurrance of the failure. Once you start the replacement compressor, test all operating paramters. Add any safety components to the system if you observe an abnormally only the tech on site will be able to locate. Good luck !!!
Do you know what terminal it blew? What kind of application is the R-22 hermetic compressor running? Well you get where i'm diggin at but much more information is required in order to better assist you Mr. Rackrookie. And you say coils were visually ok? What about the electrical integrity, ohms of resistance?
Fusite Failure !!
Obviously you seen ten times more terminal failures than some of us. You attribute the failure to high head pressure, please explain - if older hermetics have the can at near return gas temp and are common to the suction pressure - the premature failure occurs how ? From just massive overheating of the compressor and oil, etc. ???
i see it all the time on 5 ton copeland scrolls, they use stake on connectors at the compressor. these usually get weak from heat cycles and either burn the stud out of the compressor or the wire burns off the stake on. i have only seen this on units without head pressure safties and units that have a high load with longer run times, that is why most of the replacement compressors have screw terminals now. in your case the same problem might have happend with heat cycling and the seal let go at the terminal instead of the wire connector
mine were mostly roof top units varying sizes, some h.p. all were old junk equipment for the most part with no head preasure controls, only one time did we ever replace a comp and it only lasted a few months in a h.p., we worked a deal and sold him a new unit after the failure from our comp, even though he wouldnt budge the first time we told him not to do a comp.
matt
matt
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445 Posts
Well the wiring Terminals on a hermetic compressor are the weakest link.
I came across a unit almost 2 months ago with a blown out Terminal on the compressor, and a dead Condenser fan motor (siezed up). So it wouldn't hurt to check out all the fan motors. I've only seen those terminals blow out for two reasons, one from the motor shorting out because of acidic oil (breaking down the varnish on the internal motor wires), and or very high refrigerant pressure (500psi +).
I came across a unit almost 2 months ago with a blown out Terminal on the compressor, and a dead Condenser fan motor (siezed up). So it wouldn't hurt to check out all the fan motors. I've only seen those terminals blow out for two reasons, one from the motor shorting out because of acidic oil (breaking down the varnish on the internal motor wires), and or very high refrigerant pressure (500psi +).
I have had a terminal blow while standing next to the condenser, not a pleasent time. I was trying to get a single phase, 3 ton compressor that was locked up to start and had applied a hard start kit. As I flipped the breaker on the meter went to lock rotor amps for about 2 seconds and BOOM
. The terminal blew out and so did the refrigerent, and nearly the bottom of my pants.
As stated before, this was the weakest link and the terminal could not take the high amperage being pulled and it let go.
I don't know if this is the only reason for failure of a terminal.
. The terminal blew out and so did the refrigerent, and nearly the bottom of my pants. As stated before, this was the weakest link and the terminal could not take the high amperage being pulled and it let go.
I don't know if this is the only reason for failure of a terminal.
stand aside
I had a lug blow out on me several years ago, old unit at a school; I was installing new connectors on a hot compressor (don't advise that)That thing shot out like a .22, probably accross the street; they evacuated the classroom due to the mushroom cloud. I'm glad I was standing aside. Coulda poked my eye out with that thing. It's recommended to take the pressure off the compressor when doing terminal work. On larger systems, valve off the compressor, and recover it.
The terminal covers are on there for a reason. Be safe.
_____________________________________
We're not satisfied, until You're not satisfied
It was probably cycling on overload before it blew. Hot,hot!
I had a lug blow out on me several years ago, old unit at a school; I was installing new connectors on a hot compressor (don't advise that)That thing shot out like a .22, probably accross the street; they evacuated the classroom due to the mushroom cloud. I'm glad I was standing aside. Coulda poked my eye out with that thing. It's recommended to take the pressure off the compressor when doing terminal work. On larger systems, valve off the compressor, and recover it.
The terminal covers are on there for a reason. Be safe.
_____________________________________
We're not satisfied, until You're not satisfied
Was talk'in to a client some yrs back and advised unit might blow anytime--then did!! Hot oil bath and could have blown a knee out!! Even nowdays I stay at a clear angle and more or less hope! Oh, by the way , client so spooked he bought a total system change out.
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3,032 Posts
It happened to me once.Since then at least some times I use the safety goggles..
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