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-   -   Trane Heat pump capacitor exploded! (http://www.diychatroom.com/f17/trane-heat-pump-capacitor-exploded-91554/)

swiffy25 01-06-2011 08:08 PM

Trane Heat pump capacitor exploded!
 
My 12 year old Trane XE1200 heat pump stopped working the other week, and it would trip the breaker everytime i reset the breaker.

I called in a HVAC tech from the local yellowpages, and they could not find the problem after replacing a bunch of parts (t-stat, therm, defrost board, capacitors), and did some rewiring. So i called in my friend / HVAC tech to diagnose the problem, and he was looking at the wiring at the heat pump unit. He replaced the contactor, but it would still trip the breaker. He then saw the two wires (red and black, thick) coming out of the unit (maybe the compressor or fan?) that connects to the contactor.

It is a 2 pole contactor. The black wire coming from inside the unit attaches to pole #1 on the Terminal side, and the red wire attaches to pole # 2 on the Low side.

He removed the red wire from the low side on pole # 1 of the contactor, and pressed the test button on the contactor, and the unit started! I went to feel the heat registers indoors and they were very hot (hotter than aux heat alone, so i know the heat pump was working). Thinking he somehow fixed it (by removing a wire?) we went back outside, and we noticed the motor capacitor starting to smoke, and it literally exploded. It was a tight roll of paper inside that popped out.

Now, he said he will come back next time, but does anyone know what the exact problem woudl be? Could it be a bad capacitors ? He suggested that the compressor could be the problem, but why would there still be heat when the unit was on?

hvactech126 01-06-2011 08:23 PM

hard start capacitors do fail like that. nothing more, nothing less

swiffy25 01-06-2011 08:40 PM

Quote:

Originally Posted by hvactech126 (Post 564344)
hard start capacitors do fail like that. nothing more, nothing less

Do you know if it is safe to replace the capacitor and keep the unit running with the one wire disconnected?

hvactech126 01-06-2011 09:29 PM

well, you need to know what the wire went to?! if it is the black capacitor, then you need to replace it as a kit with the relay. was the wire red or purple that was removed? check your crankcase heater. They are known to have the wiring fail and short out.

swiffy25 01-06-2011 09:49 PM

Quote:

Originally Posted by hvactech126 (Post 564399)
well, you need to know what the wire went to?! if it is the black capacitor, then you need to replace it as a kit with the relay. was the wire red or purple that was removed? check your crankcase heater. They are known to have the wiring fail and short out.

Yes the capacitor is black (145-175 mfd, 330vac). What do you mean as a kit? I was planning to replace the capacitor. it was a red wire that was removed. (There is a purple wire, but that wire is already removed and tapped off from before).

I am guessing it is the CC heater since all other functions work. How do i find the specs to replaced the CC heater? Thanks for your help

hvactech126 01-06-2011 10:59 PM

that is a start capacitor, not a run capacitor. replace both the capacitor and the potential relay

CC heater

swiffy25 01-06-2011 11:32 PM

Thank you hvactech126. I am just guessing it is the CCH. Is the CCH suppose to be powered only when the contactor is pulled? Because the way it is wired now, only when the tstat calls for heat are these two wires in a connected circuit.

swiffy25 01-07-2011 02:58 AM

So as it turns out, the red wire that was disconnected was actually one of the three wires for the compressor. Apparently the crank case heater was disconnected awhile ago (snipped off). I am assuming with the wire disconnected, it caused the capacitor to blow up? What is the reason for a short like this in the compressor?

hvactech126 01-07-2011 07:05 AM

ok. cc heater is on incoming side of contactor. It is powered 24/7 so you don't slog the compressor with liquid. As far as your wires to compressor go, on the compressor is the electrical box. remove this cover and ensure that the short is not in the wiring. then next thing to do is ohm the compressor windings. Also check the windings for shorts to ground. this may be best to leave to a pro. However, there are a lot of compressors that are falsely condemned. Research your contractor b4 choosing. Average life on a HP or AC is 12 - 15 in my area.

swiffy25 01-07-2011 06:24 PM

Quote:

Originally Posted by hvactech126 (Post 564538)
ok. cc heater is on incoming side of contactor. It is powered 24/7 so you don't slog the compressor with liquid. As far as your wires to compressor go, on the compressor is the electrical box. remove this cover and ensure that the short is not in the wiring. then next thing to do is ohm the compressor windings. Also check the windings for shorts to ground. this may be best to leave to a pro. However, there are a lot of compressors that are falsely condemned. Research your contractor b4 choosing. Average life on a HP or AC is 12 - 15 in my area.

Thank you for your responses!

Last question. If I somehow get the HP to work with only 2 of the 3 wires connected on the compressor, is it safe to leave operating?

beenthere 01-07-2011 06:45 PM

Quote:

Originally Posted by swiffy25 (Post 565010)
Thank you for your responses!

Last question. If I somehow get the HP to work with only 2 of the 3 wires connected on the compressor, is it safe to leave operating?

NO.

That start cap exploded because when he removed that wire. The start cap was running the compressor.

The problem is probably in the potential relay.

swiffy25 01-07-2011 07:03 PM

Quote:

Originally Posted by beenthere (Post 565043)
NO.

That start cap exploded because when he removed that wire. The start cap was running the compressor.

The problem is probably in the potential relay.

Would a failed potential relay cause the breaker to trip instantly when tstat calls for heat/cool?

beenthere 01-07-2011 07:06 PM

Yes it can.

swiffy25 01-18-2011 05:28 PM

I have just replaced both the capacitor and the relay. However, calling for heat still continues to trip the breaker. I have basically replaced everything in the control panel that i can replace, other than the fan relay. I am out of ideas.

hvactech126 01-18-2011 06:15 PM

cc heater is or is not hooked up? compressor could be shorted to ground. if you take one component out of the circuit one at a time you can find out what is shorted. remove the component completely out of the circuit by removing the wiring from the contactor and or capacitor. start with cc heater, then fan, then compressor. are you sure you have everything connected properly? if you have replaced the dual run capacitor (if it uses one) and you hooked the fan and compressor up backwards it could cause the compressor to pull too many amps.


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