double take

Tell us your HVAC crazy and funny stories.

double take

Postby nomadpeo » Mon Jan 31, 2011 11:25 pm

i have a customer at a production plant near houston. one of the offices has a 5 ton condensing unit. someone saw what appeared to be a puff of smoke coming from the unit. the maintenance man checked it out and found a start capacitor with the bottom blown out. he told me he picked up a run capacitor and a start kit and replaced them, but wanted to wait for me to start it up so i could check it out. when i got there, i began checking components and noticed there was no run capacitor and a 3 pole contactor. yes, you guessed it. the nameplate comfirmed it is a 3 ph, 480 v unit. here's the kicker. the guy told me the start kit was installed 2 years ago by another hvac service company because a breaker tripped! (the run capacitor referred to was a 5 mfd fan cap) i checked incoming voltage and found no power present. checked for shorts to ground, and sure enough, the compressor was shorted to ground and the breaker inside was tripped. evidently the start relay and capacitor blew up when the short occurred. i thought i had seen it all, but this was a new one on me. apparently the start capacitor and start relay had no effect on the system during that two years. but then again, maybe it did and it just now gave up the ghost.
nomadpeo
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- double take

Postby nomadpeo » Thu Feb 03, 2011 10:50 pm

i'm dead serious dilkey. at first i thought maybe the compressor had been changed to single phase, so i looked at everything. no run cap. 3 hot legs. 3 phase compressor. the guy actually put a hard start kit on a 3 ph cpr. since i've never seen that before, i had no idea a 3 ph compressor could run in that state, but apparently so. weird, right ? there is a single phase fan motor with a 5 mfd cap. the start kit was a standard 5-2-1 kit purchased in a package. i opened up the relay and it was totally smoked and the bottom had exploded off the cap.
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