thermal overload

[el_coyote2373]

i learned something new today. i was checking the windings on a compresser on a ruud 5 ton condenser and i was getting open line on common and start...and common and run. i thought the compresser was bad but another tech told me to try cooling the compressor down and re-check the windings. he was right.

[Southern Mech]

many a compressor have been condemed for this. In the schematic drawing for the compressor you will see this O/L.

made the same mistake many moons ago when fresh in the trade.

[el_coyote2373]

yep. im new to the trade and running calls by my self. so i look at everything over and over and ask other techs on the phone lots of questions.

[R123]

On a single phase compressor, if your open from common to start or common to run but you have normal resistance from run to start, then your overload is open. Look at the compressor wiring diagram and you'll see that the overload is in the common circuit and you'll see why you'll have continuity from run to start. In addition to cooling down the compressor, I gently tap the compressor with a hammer by the overload and sometimes it closes it.

[Southern Mech]

another thing to learn here is, they just don't open by themselves, find the problem.

[el_coyote2373]

thanks guys. yea the compressor was super hot so i went and checked the air filter and it was 100% clogged. i mean a freaking blanket. by the way where is the overload on it?

[Southern Mech]

thanks guys. yea the compressor was super hot so i went and checked the air filter and it was 100% clogged. i mean a freaking blanket. by the way where is the overload on it?

on A/C and H/P they are internal, hence internal overload/ IOL. on refrigeration reach ins and small ptac style, there in the terminal cap and can be replaced.

[karsthuntr]

A compressor is like a body, its not dead until its cold and dead.

[MetroAir]

Do a continuity test right off your contactor between the red and black/blue wire (Trane unit). If your meter doesn't beep then circuit is open (internal overload). I get out my alligator clips and hook my meter up to both wires. I hose down the compressor till my meter starts beeping showing continuity again. Put the cover back on and start it up. Just a little trick of the trade. If my schedule is backed up I will blast a compressor with liquid refrigerant to cool it off quick. Always check your run or start cap first too. normally a failed condenser fan or low refrig charge is what caused the compressor to go into internal overload. Good luck!

[R123]

If my schedule is backed up I will blast a compressor with liquid refrigerant to cool it off quick

I can't believe that I'm reading a comment like this from a professional member!

[el_coyote2373]

yep. it is a 410a system and the pressures were 160/320. the condenser fan motor was running when i showed up and the cap was good. the only thing i found was the dirty filter.

[Southern Mech]

I can't believe that I'm reading a comment like this from a professional member!

I know right? WTF

[R123]

And he has a lot of identifying info on his profile. He may not be a Trane Comfort Specialist much longer by admitting that on the internet.