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Coach AC problem
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giantart
Posted 2019-03-19 2:17 AM (#6312)
Subject: Coach AC problem


Hi all,
So basically my question is about why my AC has started popping fuses. I have had my bus for over five years and have never had a problem running the AC units for an extended period of time. But now I started having fuses blow after running fine all day long. Granted it gets hot here in Texas but never had a problem till last year. I went through 4-5 fuses. And the period it took them to blow has gotten shorter and shorter.

I have read everything I could on the subject and had two "AC people" come out last year but never discovered the problem. The compressor doesn't seem to ever overheat. It is not vibrating and there doesn't seem to be any spikes it amperage. Runs right at the 19 or so amps that it should. I have also checked all of the wiring from the breaker box to the junction box in the closet - and nothing suspicious found. Also the units have the correct amount of freon.

And yet, the ac will blow a fuse in time frames from: 2hrs to 12hrs. Midday, night, mornings. Hotter than anything or cool outside - still seems to eventually blow the fuse.

Also I might mention that my electric bills in the summer, with one unit running, are approx. $250 per month. A window unit in my area generally sees $90-135 costs during summer.

Any and all help will be appreciated.

Jerome
#215
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LCAC_Man
Posted 2019-03-19 9:31 PM (#6313 - in reply to #6312)
Subject: Re: Coach AC problem


Elite Veteran

5001001001002525
Location: Oceanside, CA
45yr old compressor motor bearings/wear parts are only going to last so long, internal friction is going to increase and current draw will as well..
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byegorge
Posted 2019-03-20 9:09 AM (#6314 - in reply to #6312)
Subject: Re: Coach AC problem


Veteran

1002525
Location: Olympia, Washington
As I understand it he is monitoring the current draw during the event and notes nothing out of line. I was thinking like you old equipment dragging along I would expect the current draw to steadily increase over time until it pops the breaker. I would also expect it to be consistent each time (same temperature conditions would generate similar times to pop the breaker). I am going out on a limb here and suggest the breaker may be faulty and pops inconsistently.
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LCAC_Man
Posted 2019-03-20 10:05 AM (#6315 - in reply to #6312)
Subject: Re: Coach AC problem


Elite Veteran

5001001001002525
Location: Oceanside, CA
I didn't glean that he was monitoring the current when it actually failed, only that he monitored it and at some later time it failed.
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BigRabbitMan
Posted 2019-03-20 10:16 AM (#6316 - in reply to #6315)
Subject: Re: Coach AC problem



Expert

100010010025
Location: Cottage Grove, OR
To replace the breaker would be a good first effort. I had one start tripping and replaced it and all has been good since. I had it happen with both with the coach and my house!
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dkarnath
Posted 2019-03-20 11:09 AM (#6318 - in reply to #6312)
Subject: Re: Coach AC problem


Elite Veteran

5001002525
Location: Medford, OR
We don't even know if he's talking about the original AC units for sure? AND there is two breakers, one for AC 1 and 2. Which one is tripping fuses? Each AC has it's own pigtail that lays on top of the units, maybe some wiring is rubbing somewhere. I would start by pulling the units out and cleaning, inspecting, and putting some 30w on the bearings.

http://www.fmcmotorcoach.com/files/Manual/39_11012v.pdf

http://www.fmcowners.com/mbbs22/photos/show-album.asp?albumid=112&p...



Edited by dkarnath 2019-03-20 11:11 AM
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giantart
Posted 2019-03-20 4:24 PM (#6319 - in reply to #6318)
Subject: Re: Coach AC problem


They are the original units, and both units are popping fuses. Where would i find a "New breaker"? And could the cartridge fuse breakers be replaced with more standard type breakers?
Thanks.
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giantart
Posted 2019-03-20 5:14 PM (#6320 - in reply to #6316)
Subject: Re: Coach AC problem


Hi Stephen - I appreciate the help. Might you have a part number or manufacturer's model number for a "new breaker"?
Thanks
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BigRabbitMan
Posted 2019-03-20 11:16 PM (#6321 - in reply to #6320)
Subject: Re: Coach AC problem



Expert

100010010025
Location: Cottage Grove, OR
giantart - 2019-03-20 3:14 PM Hi Stephen - I appreciate the help. Might you have a part number or manufacturer's model number for a "new breaker"? Thanks


My bad!
You did say fuses and somehow it got switched over to breakers. The ac circuits have fuses and not breakers so the discussion relative to breakers is not relevant. I did have a breaker problem for a non-ac circuit.

At this point I am stumped as I do not know what the normal current draw should be so I don’t know where to start looking for the problem. Do you know if your measured amps matches with the designed current draw?
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BigRabbitMan
Posted 2019-03-21 12:46 PM (#6322 - in reply to #6312)
Subject: Re: Coach AC problem



Expert

100010010025
Location: Cottage Grove, OR
Per Eric Whedon, an AC professional.

Things to check,
1. Winter plate under coach removed?
2. Outdoor fan motor bearings axial/radial free play
3. Oil indoor, and outdoor motor bearings. (Use non detergent SAE 30 oil)
4. Check fan motor run capacitor actual MFD.
5. Check compressor run capacitor actual MFD. (this will cause high amp draw)
6. Verify compressor start capacitor is not open circuit , or has ruptured vent.
7. Check potential relay. Terminals 1-2 less than 5 ohms. Terminals 2-5 between 10-1000 ohms
8. Breaker must be HACR type.
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giantart
Posted 2019-03-21 6:39 PM (#6324 - in reply to #6318)
Subject: Re: Coach AC problem


"He" thanks you for the help and links.
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BigRabbitMan
Posted 2019-03-21 11:01 PM (#6326 - in reply to #6312)
Subject: Re: Coach AC problem



Expert

100010010025
Location: Cottage Grove, OR
Additional information from Eric

Add this! The Coaches originally came with Square D brand QO type fuse holders. The correct fuse is a SC20. Replace the fuse, run the A/C for 30 Minutes. Remove fuse holder, if fuse holder is warm (or hot) replace the fuse holder assembly.
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giantart
Posted 2019-03-22 3:06 PM (#6328 - in reply to #6326)
Subject: Re: Coach AC problem


Thank you guys - I appreciate the help very much.
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giantart
Posted 2019-03-22 3:24 PM (#6329 - in reply to #6328)
Subject: Re: Coach AC problem


How about the model number for the squared D QO fuse holder itself? I know which fuse it takes but don't know what the model # of the actual breaker is.

-And yes, the breaker gets(And is) hot when fuse blows-

As you are probably aware; when one goes to google these days, and searches "Square D brand QO type fuse holder", dumbgoogle shows you every other product except what you are searching for. So if anyone knows the actual number for breaker, that would help.
Thanks all!
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