AC overloaded-now nothing

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hilogreen

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New to RV's, but...
I had the ac running on my 94 hilo, and I turned the thermo switch from hi to low, cutting off the compressor, and trying to cut it on again. Needless to say, it overloaded the compressor, and threw the breaker in my shop (from which my drop chord was running). I shut the ac off and reset the shop breaker.  Only now, the ac won't do a thing. No fan, no compressor, nothing. The breaker in the rv was not thrown, and I have limited paperwork for this camper. Its a 94 towlite hilo. All outlets etc are working. Just no ac. I cannot find a fuse, only that breaker box.  Any ideas?
Thanks,
Matthew
 

Gary RV_Wizard

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What make & model is the a/c unit?

There are no fuses that I am aware of on any RV a/c circuit board and the breaker will be the only thing in the trailer itself that opens the circuit.  I'm afraid you may need professional help with this problem.

Can you test to be sure 120 VAC power is actually reaching the air conditioner?  If so, it seems likely that something on the a/c circuit board has blown out.  If not, then something has burned out in the trailer power system. However, that seems unlikley since the trailer's breaker did not trip - the shop breaker went first.
 

hilogreen

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Gary, it is a Duo-therm 579 series BRISK AIR or QUICK COOL.

The model number is 991731650 serial number is 40319597.

I will test the breaker to make sure it is ok, and make sure there is power to the ac unit tomorrow. I bought a tester today. 

If there is power to the ac, then I'm leaning towards ac's circuit board as well.  Is this something I can fix myself if it is the board?

I don't understand why the shop breaker would trip AND the ac would be damaged. Seems like one or the other would have happened.

Thank you again.
 

Jim Dick

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Hi Matthew,

How long did you wait before deciding the A/C wasn't working? Once you shut it down it takes a few minutes before it will restart. There is pressure on the head of the compressor which must be bled down before restarting. If you waited several minutes then you might have another problem.
 

hilogreen

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Aug 12, 2006
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Jim and Gary,
Yeah, its been days. This happened Saturday. I went out and tested the wires going to the ac this morning with the tester I bought this weekend. There is no power going to the ac. So, apparently, in addition to tripping the breaker in my shop, somewhere there is a closed circuit in the camper.  Any ideas?  All I can determine is the breaker. I guess I can try to determine if the breaker itself went bad (the one in the camper). 
 

John From Detroit

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Usually there is indeed a breaker in the camper for the AC,  See if you can identify it And open the panel (Since it appears you know how to do that safely) check for 120vac at the breaker itself, If there is none, cycle the breaker, not all of them indicate "Tripped" well, in fact, cycle it before you even open the panel... If that fixes it, label it (if not already labeled) and praise the powers that be.

If not, try re-seating it, Yes, they can come loose,  Last step, replace it
 

hilogreen

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John, Thanks. I've cycled the breaker a few times. I'll check to see that it is seated. I'll also pull it and check the power into the breaker to make sure that is still good. If the breaker is good, what else can it be?
Matthew
 

hilogreen

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Breaker seems fine. I put the voltmeter on the breaker wires hot and ground. I get 119 volts. When I flip the breaker to off, 0 volts. Seems to be fine. So somewhere between the breaker and the ac, I'm losing power.
No idea how. All outlets are working fine.
???

I'm going to run a hotwire from a dropcord to the ac and see if it comes on I think.
 

John From Detroit

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Well..... In theory there is a single wire (Well, standard 12/3) going from said breaker to the AC, no breaks, no junctions, In theory

In practice I'd not guarentee it.  There may be a junction somewhere

However if you have power at one end of the wire, and none at the other end of the wire... You have a burned out wire.  Replacment is the only option,  Unless... Of course.... You were testing the wrong breaker.  Alas, more help I can give  but it has to be hands on as I have tools to test wires powered down here
 

John From Detroit

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Possible yes, but he said "There is no power going to the AC,  and later said "power is coming out of the breaker"

I won't state he tested the proper wire pair at the AC (I'm kind of assuming he knows what he's doing there)

I know the Carrier V's in this rig give me enough fits I'm considering installing a permenate power monitor panel so that I can check at a glance to see what has and what has not got power (AC main, Blower & Compressor) dang thing wouldn't cost a dollar to build
 

hilogreen

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Yeah, I pretty much know the basics.
At the breaker, and at the ac, there is a white, black, and copper wire.  The voltmeter goes on the white and black, and that read me 119.  It looks like basic house wiring. But no power at the ac. By the way, I tested all breakers, so none of them are defective.
 

Ken & Sheila

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When you call your rig a hilo, is it like a HI-LO, where the upper half lowers for transit? If so, the standard romex wiring is converted to something like SO cable (flexible cable) for the portion that is moved. There would be junction boxes at both ends of the SO cable. If this is true check voltage at each box.

ken
 

hilogreen

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Yeah, thats it, a HI LO, the upper half raises and lowers.  I've not seen those junction boxes. Any idea where they might be?
Thanks so much-I'm learning,
Matthew
 

Lou Schneider

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Look for a black coiled cord that goes between the top and bottom units.  The junction boxes will be on both ends of it.
 

hilogreen

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Haven't seen it. This is a 94 model. Would it plug in, or are the wires connected in another manner?
 

hilogreen

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GREAT! It was the junction box.  I had actually unhooked it as I was tackling another project in the camper.  I had no idea they were related, and had the back blocked off, so I couldn't even see it to remind myself I had tinkered back there. Lessons learned.
Now I have to more on the the fridge-it was working, now is not.
THANK YOU ALL>
Matthew
 

John From Detroit

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Glad you found it.  As for the fridge, what's wrong with it,  Have you checked the 12 vdc?  With the back of the trailer "off" you may have disconnected the converter which keeps the batteries charged and thus no 12vdc
 

hilogreen

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Well, the fridge "seemed" to be working when we were diagnosing the ac problem. I say seemed because there was frozen water in the icebox and the racks felt cold to the touch in the fridge, but I did not put a bottle of water in it to see if it kept it cold.  I have the batteries in my shop, and just have the trailer plugged in to my shop electricity, so the fridge was running on ac, not 12vdc.  But now it is not cold. I have yet to locate its power cord. It is a dual electric/gas unit.
 

Karl

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The power cord may be plugged into a receptacle inside the access panel located on the outside of the hi-lo, or may be permanently wired in a junction box there. Do you get any indicator lights above the refrigerator inside like a/c, auto, gas or check? If the check light is on, you need to turn off the power switch and then turn it back on. If you get no lights, check your 12 volt fuses.
 
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