Basement AC Compressor #2 overamps blows breaker

jeffro · 06-30-2013, 11:55 AM

2005 Itasca Horizon 40FD basement unit. The AC never seemed to cool enough and I now know why. When activated Compressor#1 comes on and runs just fine, seconds later Compressor#2 activates and the EMS ampmeter shows amperage at 65 or greater and then the Comp#2 breaker trips. Any ideas where to look to repair.

Thanks in advance for any wisdom and suggestions.

bobbyl · 06-30-2013, 12:04 PM

Most likely cause is the #2 compressor is locked up. This would explain the high amps and breaker trip.

Harry B · 06-30-2013, 05:39 PM

I had the same thing. Turned out it was a bad exhaust fan motor (Higjh speed winding) as it goes into high speed mode with both compressors on. As mentioned it could also be a locked or shorted compressor. In either of these cases the unit has to be pulled to repair it. Not fun

DancinCampers · 07-01-2013, 10:48 AM

Check the #2 compressor start capacitor, especially the attached little black square PTCR device attached on top. Start cap should be black and round.

Don't let the compressor try to start for any long length of time, as internal overload device could be damaged.

jeffro · 07-01-2013, 05:35 PM

Thanks for the advice from everyone. Local shop says caps are ok. Seems we may be looking at locked up compressor (?) Anything internal needing repair is not easy on these basement units. I'll let you know what we find.

Harry B · 07-01-2013, 08:45 PM

They are straight forward to work on once they are out. Most of the labor is in removing and reinstalling the unit. Fork lift is the key to making it easier. You also might consider replacing the squirel cage on the exhaust fan while you are in there. They do get squeaky. my AC got quite a bit quieter with the new cage. Good luck

pameridan04 · 07-03-2013, 01:17 PM

Same thing happened to my#2 , Exhaust Fan Motor also.

PAM4

Duner · 07-10-2013, 04:00 PM

Back in 2008 my basement A/C outdoor blower bearing went out. I replaced it myself and documented the procedure. Many members on the forum have used my write-up to successfully do their own repairs. It's pretty straightforward and you don't have to be an a/c wizz. Also if you read it you will get some tips that you can have a repair tech look at if you decide to pay a guy to do the work.

Here's a link to download A/C Removal Procedure.

All the Coleman basement units use a brass bearing on both the indoor and outdoor blowers that wear out if they are not lubed with a few drops of oil every year. Of course nobody does that because it's too muchof a PITA and there's nothing in the manual to tell you it's needed. On the roof a/c units (which use the very same brass bearing), Coleman manual says maintenance requirement to oil these guys once a year. In my procedure, I have the part number of a sealed ball bearing replacement that will last a lifetime.

The other common problem is with the metal squirrel cage fatiguing over time and they will get noisy, start to wobble and crack. It is well worth the money to use the new composite plastic squirrel cage......unit is much quieter and draws about 1 amp less power.

Good luck,
Bill

UFO Pilot · 07-10-2013, 04:07 PM

My over amperage problem was due to bad starting capacitors for the fans. The fans come on before the compressors engage and if the fans don't start the compressors won't run. That is the way the RV repair man explained it to me. When you remove the outside AC cover there is a small "door" in the upper left side. The "door" has 3 or 4 screws holding it on. Removing the "door" will get you to the starting capacitors.

Jimooo · 07-10-2013, 04:51 PM

Could be start cap not enough energy to start compressor , the fans should start after compressors start up from delay switch.

You can OHM that compressor out to see if windings are shorted just to be sure before you go any further .

Good luck,

James

John Hilley · 07-10-2013, 05:02 PM

Both 30 amp and 50 amp are single phase. With the 50 to 30 amp converter the two legs of a 50 amp circuit are put on one leg plus the neutral, giving the hot side twice the wire capacity compared to the neutral. When hooked up to 50 amp you are pulling from L1 and L2 and using the common neutral.

Since the currents ‘flow’ in opposite directions we subtract to get the net current flowing in the Neutral. If L1 and L2 loads are exactly the same the Neutral current will be Zero. In fact when the loads are assigned electricians try to balance the load on Line 1 and Line 2 so that the neither leg is overloaded, the result of this is that the Neutral current should be about zero in a well designed system.

With the converter there shouldn't be a problem because it is properly sized for 30 amps, but it does carry more current then when connected to a 50 amp circuit.

ChasA · 07-11-2013, 03:20 PM

John Hilley, the part about the 50 to 30 amp adapter connecting L1 and L2 together is wrong. If it did that it would be a dead short and trip the pedestal breaker as soon as power is applied. The adapter just connects one of the input lines to the output.

John Hilley · 07-11-2013, 04:36 PM

No it is not wrong. The RV load center is not a 240 vac load center, but two 120 vac in parallel each with it's own main breaker.

ChasA · 07-15-2013, 09:35 PM

Sorry John but it is wrong. You cannot connect the 2 50 amp lines to one wire, it will blow the breaker. It has nothing to do with what you are powering. The fact is that a 50 amp pedestal supplies 2 120 volt 50 amp lines that are 180º out of phase, and if you measure volts between the 2 hot lines, it will be 240 volts. The RV does not use the hot lines in this manner. It uses the hot lines separately, creating 2 separate 50 amp 120 volt circuits. Circuit 1 loads will be connected to line 1 and the common neutral, circuit 2 will be connected to line 2 and the common neutral.

John Hilley · 07-15-2013, 10:46 PM

Quote:

Originally Posted by ChasA

Sorry John but it is wrong. You cannot connect the 2 50 amp lines to one wire, it will blow the breaker. It has nothing to do with what you are powering. The fact is that a 50 amp pedestal supplies 2 120 volt 50 amp lines that are 180º out of phase, and if you measure volts between the 2 hot lines, it will be 240 volts. The RV does not use the hot lines in this manner. It uses the hot lines separately, creating 2 separate 50 amp 120 volt circuits. Circuit 1 loads will be connected to line 1 and the common neutral, circuit 2 will be connected to line 2 and the common neutral.

Reread what I posted above. The adapter takes 120 VAC circuit 1 and 120 VAC circuit 2 and connects them in parallel to the 120 VAC 30 AMP receptacle on the pedestal. What was 100 amps of capacity in the RV Load Center is reduced to 30 amps. No shorts, just two 120 VAC, 50 amp circuits bridged and plugged into a another 120 VAC circuit. There isn't 240 VAC any place in this configuration.

John Hilley · 07-15-2013, 10:56 PM

ChasA, I think we are talking about opposite pigtails. I am talking about a 30 amp male plug to a 50 amp female receptacle. This feeds 120 VAC to each of the two 120 VAC sides of the load center sharing 30 amps. I think you are talking about a 50 amp male plug to a 30 amp female receptacle.

ChasA · 07-16-2013, 06:43 AM

John Hilley, you are right, I was talking about 50 amp male to 30 amp female. I tend to describe adapters in terms of source to load. I would call the adapter you're talking about a 30 amp to 50 amp adapter. Glad we got that cleared up.