Fried Contactor


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Old 06-28-08, 11:44 AM
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Fried Contactor

Last saturday our Power went out for about 7 hours. First just the 220 then the whole thing. An overhead line had come loose in the neighbors yard. About 6 houses were w/out power.

Sunday the air didn't seem to be quite as cold. Climbed on the roof, checked the evap coil- clean. The blower motor fan blades were dirty but not crazy dirty. We cleaned the condenser coil & fins because they were dirty but again nothing horrible. Checked the split and it seemed to be working fine. All this week I've been up and down off the ladder checking the split, sometimes it's 20, 17 or 12. Something didn't seem quite right.

This morning we woke up and it was warm. 77 in the house when it was set at 74. Not normal for overnight and it's hot here but not overly hot. About 108 yesterday. Instead of turning the unit off and climbing on the roof. I just went up there. The compressor and fan were not running.
Turned the unit off, opened the wiring cabinet...looked for obvious signs of fried wires. made sure all the contacts were tight, turned the unit back on and it cooled just fine. But I'm not optimistic enough to think that all is well...oh no.
Had an early appt and came home to a semi cool house but a 10 degree split. GAH!

Back on the roof, opened the cabinet - inspected again- carefully this time and saw this wobbly little contactor with a tiny little spring like thing half way out.
It's hard to tell in the photo but it looks fried.
http://img241.imageshack.us/img241/7964/aircoc9.jpg


I think that perhaps it was working intermittently and that's why sometimes the air would be cold and other times the blower and compressor were probably off. I can't hear the compressor from inside the house.
I wish our unit was on the ground. I have half a mind to install a camera on the roof to monitor the unit.

I looked up the model number and this is it HQ1050839PU for 130.44
However, our local part store only had a dual pole and mine is a single pole. Theirs was only 30.00 but the tech said use a jumper wire from L2 to T2.

The price difference and the "jumper wire" make me nervous.

My questions are - does this sound okay? I would hate to fry my compressor and fan - Really hate it.

Do you think the power outage fried my contactor or at least lead to it crappin' out?


btw, I have an arcoaire 4ton gas pack unit.
 
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Old 06-28-08, 12:33 PM
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contact impedance test

At rated current, good relay/contactor contacts show < 30 mV drop across them, bad > 100 mV.

If your voltmeter doesn't read that low, you can use a doorbell transformer to step up the voltage into your meter. You'll get about 20% more than the 120/16 or 120/24 ratio that you'd expect.

Since bolted connnections put a lot more pressure on the contact interface, the v drop across these should be way less than 30 mV at rated current.
 
 

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