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Posted: 6/11/2009 3:09:34 PM EST
[Last Edit: 6/11/2009 3:11:42 PM EST by TexasSmooth]
I first noticed this 2 days ago and thought it was odd that my blower motor was still running but yet was not cooling. Low and behold the compressor had tripped the breaker. So I shut everything down and reset the breaker. Everything was running smooth once again.

The next day the same thing happened again as I first noticed it when I got home and the compressor was not running again. Yep, tripped breaker. I began to suspect that there may be ants or some crap getting up in the electrical area. So I pulled that panel off and everything looks fine. Contactor still intact, no leaks from the caps, wiring still ok.

Today has been the worst yet. Since I've been home the breaker has tripped 4 times. Now keep in mind I'm referring to the breaker in my breaker box, not the outside disconnect. That disconnect by the way is also in good condition, nothing wrong after visual examination. I began to suspect that maybe the breaker itself or the wiring may be at fault. The wiring for this circuit is still aluminum (it's an old house). I had planned to replace it with copper this past winter but other stuff ate up my time...I suspected possible "creep" in the wiring albeit a longshot. So I pulled the door off and yes, the wiring inside the breaker box is still ok and tight.

I'm at my wits end on this one. I'm going to have to wait until tomorrow to call my regular a/c guy, but tonight I may not get any sleep because of this because I do sleep best at a certain temperature. Could it be the breaker in the box going out? If there are other possibilities I'd certainly appreciate suggestions.

ETA: I'm going to try and swap the breaker. It just tripped again and the breaker was hot. None of the other breakers were, and neither was the master breaker for the whole box.
Link Posted: 6/11/2009 4:04:00 PM EST
[Last Edit: 6/11/2009 4:04:55 PM EST by I_M_2_SANE]
I'm not an A/C pro, But I did stay at a Holiday Inn last night.

I've worked on machines with compressors/large motors though.

I'd look at the contactor and the capacitors. Check the contactor's points and see if they are corroded.

You may want to be next to the unit and have someone call for the compressor to come on and see what the unit is actually doing when the breaker trips.
Link Posted: 6/11/2009 4:12:09 PM EST
Ok I've replaced the breaker and it's back on. We'll see if it's able to stay on for a while now.

Here's a picture of the compressor's wiring. Everything looks ok to me. Contactor not corroded, no leaks on caps, wiring is ok.
Link Posted: 6/11/2009 4:12:38 PM EST
[Last Edit: 6/11/2009 4:14:46 PM EST by sav_carguy]
Your best option at the moment is to call a professional HVAC guy. Chances are , you've got either a faulty capacitor , or the compressor is starting to go , and the extra mechanical resistance of the compressor failing is causing it to draw too much current. If the breaker is hot to the touch , that usually means there is too much continuous current flowing through it , but if you've got a spare to try , it shouldn't hurt to swap it and see what happens.

ETA - From your pic , one of the caps looks newer. Have you had this problem before?
Link Posted: 6/11/2009 5:54:25 PM EST
[Last Edit: 6/11/2009 5:55:22 PM EST by TexasSmooth]
Ok I've swapped out the breaker and so far it has not tripped. I'm keeping my fingers crossed that that was the problem.

sav_carguy: I amped the circuit while it was running and it was drawing around 23-24A, which is normal for the unit. The increased resistance you mentioned though would make sense producing increased electrical draw. Is there any way to tell if a cap is about to go? The only thing I really know to look for is a leak or possible bulge. The only thing I've replaced recently was a contactor about 2 years ago due to ants. If the cap has been replaced it must have been the previous owner. I can get a close-up shot if you want.
Link Posted: 6/11/2009 6:28:11 PM EST
TexaSmooth. I had an older home that used to trip "many" breakers. I ended up buying a case of new Square D's and just swapped out the entire fuse box. After that they did not trip.

Link Posted: 6/11/2009 6:33:29 PM EST
[Last Edit: 6/11/2009 6:35:25 PM EST by fxntime]
Change the breaker. Depower the unit, pull a wire off the capacitor/s and check to see if it's within 6% of it's rated capacity. If not, replace it. Remember, they can hold juice so don't go touching it across the connectors.

And make sure the fins are clean..............if not, hose out against the dirt and crap, don't push it deeper into the fins.
Link Posted: 6/12/2009 1:47:14 AM EST
Just woke up this morning and the new breaker did not trip last night and the house is cool. So far so good.
Link Posted: 6/14/2009 8:00:45 AM EST
Being in the trade, I have seen units do the same thing because the outdoor coil was crapped up. The discharge pressure would creep up as the unit ran longer, causing the compresser to creep up also till the breaker would trip.
If you have a decent strap on thermometer you can check to see if your coil is crapped up. Just strap it to the liquid line(the smaller of the two pipes to the unit) Then compare that temp to the outdoor temp.
0-15deg differance good to go
15-25deg diff think about getting the coil cleaned
+25deg get your coil cleaned
Link Posted: 6/14/2009 1:06:37 PM EST
Originally Posted By TexasSmooth:
Just woke up this morning and the new breaker did not trip last night and the house is cool. So far so good.

BTDT several years back with a breaker at my mother's house. Vacuum cleaner used to trip it every time. Replacing the breaker was the cure. It seemingly tripped with less than a 15 amp load.

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