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Darrbaby
11-07-2012, 02:33 AM
Hello and thanks in advance for the info....
I have a condencer fan motor trying to run when the contactor is open this contactor is a single pole so i assume that the power is feeding through. When I energize the contactor it trips the breaker instantly would i assume the compressor has a short in it or is the fan motor going out the capacitor is good and reading micro ferits that it should? Thanks again....

martinw58
11-07-2012, 06:27 AM
try disconecting the fan and check voltage through the contactor the contacts might be welded in energize with fan disconected to check the coil of contactor not faulty

monkey spanners
11-07-2012, 07:44 AM
Make a note of where the wires go and disconnect the compressor (power off) then turn the power back on. Sounds like you have a bad compressor and the power is earthing out through it due to the single pole contractor (assuming this is an American style unit)

NoNickName
11-07-2012, 07:50 AM
Neutral and live are reversed and the fan is shorted to ground. The fan is working when the contactor is open (conduction from neutral to earth), it trips when it's closed (short from live to earth).

Darrbaby
11-07-2012, 02:50 PM
Let me be a bit more clear for you guys. Contactor is good, cap. is good fan motor is 'trying to run' it moves at about 1/5 speed. I didnt think to disconnect the compressor then check to see if fan works correct or not. This is a 2 year old YORK 4 ton residental single phase unit and ALL wires are in the correct factory locations and the unit has not been tampered with at all. Can someoneprovide a link to correctly diag. the compressor as i looked and found nothing here im sure there is somthing I just never found it.

Thanks again fellas....

Darrbaby
11-07-2012, 02:51 PM
Oh the voltage is correct as well... Thanks

NoNickName
11-07-2012, 03:54 PM
Live and neutral are likely to be reversed on the incoming main breaker.

monkey spanners
11-07-2012, 09:32 PM
Live and neutral are likely to be reversed on the incoming main breaker.

Think they use two lives to these and no neutral, but only switch one live with the contactor, the other live is just on a solid link through the contactor.

Darrbaby, this is a mostly european site so your style of system and home electrical supply is not common here.

I would be checking the compressor windings for a short to ground with a megger, and testing the windings to see if they ohm out ok, if they check out ok then i'd be looking at the wires to the compressor for shorts. If they check out then test the fan motor.

NoNickName
11-07-2012, 10:48 PM
Think they use two lives to these and no neutral, but only switch one live with the contactor, the other live is just on a solid link through the contactor.



That may be the reason why it runs when open, and shorts out when closed.

Darrbaby
12-07-2012, 12:31 AM
So, It was the compressor after ohming out the windings found the short and replaced the compressor.
If this a mostley european site do you know of an american site i can browse?
Once again thanks for the help fellas.....

monkey spanners
12-07-2012, 05:40 PM
If this a mostley european site do you know of an american site i can browse?
Once again thanks for the help fellas.....

You could try Hvactalk but they will probably just tell you to call a tech to come fix it for you...

You won't get any help until they have verified you are a technician and not a homeowner, you'll need to fill out a form with all you work related qualification.