Well, guess it's my turn. Yesterday I noticed that breaker #7 was tripped. This is marked as A/C #2 so I am assuming it is for the 2nd compressors on the SCS basement units. I tracked it down to the front A/C that trips the breaker as soon as I turn the fan from Lo to Hi (which on my thermostat is how to control whether only 1 compressor LO or both compressors HI come on). I checked the breaker wires and they are tight, checked the 120v wires on both a/c circuit boards and on the rear they were tight. On the front a/c they were snug so I tightened them. But when I switch the 2nd compressor to on the breaker trips immediately.
The fans appear to be working on both front and rear.
Suggestions?
Can you isolate the wires to the compressor and hang an ammeter on it to see if it is pulling locked rotor current. It's probably one of two things. Breaker is bad, or compressor is locked.
It will be tomorrow or Sunday before I can check it. But spell it out for me, if compressor is locked does that mean bad compressor?
Forest, Like Richard stated I would check for a bad breaker 1st. You could put an Amp Meter on the legs and see what it draws or just exchange the questionable breaker with another that doesn't appear to have this problem.
Circuit Breakers do go bad occasionally so try this 1st before spending more Dough, hey also check other connectors as well! Remember Volts X Amps = Watts. Poor connections make for poor Voltage and increase Wattage, not always the case but a great place to start.
I just switched the wires on the breaker for a/c #1 & #2 and when I turned on the #2 compressor for the front a/c the breaker that I put a/c #2 on tripped immediately. The ammeter over the driver jumped over 60 amps before it tripped.
So now that I've eliminated the breaker as being bad I'll try and check the amp draw on the #2 compressor. Or maybe swap the control boards.
Not sure that a Circuit Board could create this issue, sounds more like a Fan or Compressor.
any Help here?
PS does the Fan have a Condenser? I have seen this issue before.
Steve, do you mean "does the fan have a capacitor?"
there are 4 capacitors in each double unit. when my circuit boards were re-relayed, i changed all the capacitors. i think i paid 4-5 dollars apiece for them.
if you look at the schematic on the back of the panel that covers the circuit board you will see which one is which.
tom
(08-02-2013, 08:21 PM)Fulltiming Wrote: [ -> ]Steve, do you mean "does the fan have a capacitor?"
Yes,
Been working on Patti's Air Conditioning System and I must have had a "brain fart".
Forest, I had this problem and it turned out to be several problems. First, someone had replaced the breakers with 10 amp instead of 20 amp breakers. Next, the condenser motor on the front A/C had worn out bushings, the 110 volt cable to the control board was loose, and finally, I had to rebuild the control board due to a bad relay. I think your idea of switching the control boards will isolate the problem to capacitors, fan motors or compressor. Then work from there.