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Rooftop AC troubleshooting

4rickyg

By 4rickyg
in AC, Heating, and Cooling

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4rickyg

4rickyg

Posted
Posted

2005 HR Navigator. Front a c is tripping breaker. When I first turned it on. It is reading 10 amps at the Aladdin. Then after fifteen seconds it shoots up to 50 amps and trips to breaker.

I took the cover off.Did not see any burnt wires or anything like that. The fan Spins smoothly. Don't see any leaks, Was blowing nice and cold until it tripped breaker. Could it be something simple? Should I have a Mobile repair guy come out or just replace it with a new one. I believe it is a durotherm 1500 with the heat pump.

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vito.a

vito.a

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Posted (edited)

It should be a Dometic Penguin AC.  It sounds like it's tripping the breaker when the compressor tries to start.  There is a slim chance it could be the start capacitor.  You can have it checked, but more than likely you'll need to replace it.    

The problem is going to be a new Penguin II is not compatible with the original 5 button Dometic thermostat. 

What model is your Navigator?  The 42' and longer coaches have three A/C units.  Usually, the one up front is on a single thermostat and the center and rear A/C are together on another.  

If you only replace one A/C you'll have to install it on the front and connect it to a new thermostat compatible with the new A/C.  Its kind like of like a shuffle. 

If you have a 40' model, you'll have to replace both A/C units and the thermostat.   

There may be another option.  Dometic made retrofit control boards.  If you can find one you can install it in the new A/C, and it will work with your old 5 button thermostats. 

Edited by vito.a
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Tom Cherry

Tom Cherry

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ODDS ARE…..not good.  Buy and install a new capacitor.  If that don’t work…then one could invest another $300 or so on one of the Soft Starts…but that, IMHO, is just pouring MORE money down a rat hole.

TRY the new capacitor….the Compressor is the problem….not the fan.  That Compressor eats JUICE.  As it wears….it’s addiction grows.  Again, that jump sounds like a bad capacitor….and that is the most logical “try this”.  Read up on HOW and what you need.  There are at least 10 topics here.  There is MORE “CORRECT” info on this site that most TYPICAL HVAC Techs know….

let us know….

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MyronTruex

MyronTruex

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Posted

Here is an incredible write up from Vito. I hope he doesn't mind me sharing. 

AC replacement from Vito.docx AIR CONDITIONER TROUBLESHOOTING USE THIS ONE.pdf

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Tom Cherry

Tom Cherry

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Posted
9 hours ago, 4rickyg said:

Thank you and yes it is the penguin  low profile. I believe all three a c's were replaced about nine years ago when I bought the coach. They have the new version thermostats. Fan is set to auto. I will try replacing the capacitor maybe I will get lucky..

Don't quite understand the NEW VERSION thermostats.  You should, based on my recollection of the years and such, have the Dometic 5 Button thermostats.  There has NOT been any "upgrades" by Dometic.  Your OEM HVAC system is the CCC "Multiplex" type. The controller in each one and the thermostat are that. Post a picture of the Thermostat.

However, that is sort of "beside" the point.  If the unit is up and running and the AMPS go skyhigh....then, MAYBE the controller has bad contacts. A high resistance contact may (should?) do that.

The way to TEST.  FROM the 2005 HR Sales Brochure (I'd download that from the HR site...a VALUABLE TOOL), there were either TWO or THREE HVAC's installed.  BUT, they were ALL 15K BTU units.  SO the CONTROLLERS are identical.

You need to pull the outside cover. The Control module (Dometic calls it the AC Board.  I easy to spot. Remove it.  Then do the same for another one....doesn't matter which one.  Take a picture of the DIP switch settings on them. Then, REPROGRAM or swap the DIP settings. Reinstall BOTH.  IF BOTH are GOOD....then that is the easiest.

NOW, you WILL have to reset BOTH (assuming you have multiple Thermostats). POWER OFF (the bottom switch) Hold the TOP and BOTTOM buttons (Mode and Zone). THEN, while holding....turn ON.  FF will be displayed.  NOW, if you are referring to the MICROAIR T'Stats....read the manual and do the same.  RESET.

THEN....try it out. IF the problem is NOW in the OTHER unit...bingo, the contacts on the relay are bad. You can purchase a NEW one...all you do is duplicate the DIP's.

That's the ONLY thing I could offer.  That is not a hard job. You need to TRIP all THREE AC Breakers on the 50 AMP Main Panel, for safety of COURSE...which is what you should obviously do if you swap the Capacitors.

That's it.  Post the T-Stat pictures...

BTW.  The ON/OFF switch is a HIGH failure item. MOST NEVER use it.  Use the MODE button and go to OFF.  You'll be glad you did....LOL.

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cbr046

cbr046

Posted
Posted

If the compressor doesn't spin there's no magnetic force to put inductance into the armature.  That will make current go sky high. 

If the compressor starting capacitor is bad it won't start spinning, so that would be my first choice. 

You can buy a mulitimeter that measures capacitance, current and voltage.  $20-$30 on Amazon. 

- bob

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4rickyg

4rickyg

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Posted

Thank you and yes it is the penguin  low profile. I believe all three a c's were replaced about nine years ago when I bought the coach. They have the new version thermostats. Fan is set to auto. I will try replacing the capacitor maybe I will get lucky..

This is what I referred to as newer style thermostat. I removed the capacitor, took it to Grainger supply. They tested it and said it was definitely bad. They didn't have a replacement. Found some on Amazon.  Looks like Dometic $60 and a after market $20. Think I will go with the Dometic. Will give results when I install it.  Thanks for help.

20240627_165356.jpg

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Tom Cherry

Tom Cherry

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1 hour ago, NAMVET77 said:

Vito

I tried to download your AC replacement doc and it has been removed.  Can you pm me a copy?  Thanks.

Don

hikenbike77@gmail.com

BUMMER.  The files downloaded OK for me and @Frank McElroy.

I sent you a PM with them as an attachment.

Could not find them, as I THOUGHT they would have been in the “files”…key word searches failed.

Frank will have to sort this out….and see if they should  be in our files…

BTW….that is definitely a CCC2 or the latest and standard thermostat….  Probably a bad Capacitor.  If NOT… new unit or a $350 bandaid device.   The Smart or Soft Start will not fix the issue….maybe allow it to work….but once it gets past, as in MORE SEVERE, then the only recourse, I think, is replacement….that’s my logic and understanding….

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NAMVET77

NAMVET77

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Posted

I pulled the cover off the ac on the roof and a copper line broke by what I think is the expansion tank. No one will fix it cuz no where to put in the “T’s” to pull a vacuum or charge it.  I’m not an ac guy so just guessing on the repairs. Must be true cuz everyone buys a new one vice getting it fixed. 
Don

04 Camelot 

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Ivan K

Ivan K

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Posted (edited)
30 minutes ago, NAMVET77 said:

I pulled the cover off the ac on the roof and a copper line broke by what I think is the expansion tank. No one will fix it cuz no where to put in the “T’s” to pull a vacuum or charge it.  I’m not an ac guy so just guessing on the repairs. Must be true cuz everyone buys a new one vice getting it fixed. 
Don

04 Camelot 

If it is a heat pump, they can put the T on the long line from condenser and charge it in heat pump mode. That's what I have done more than once.

IMG_20231006_115421014.jpg

Edited by Ivan K
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Bill R

Bill R

Posted
Posted (edited)
2 hours ago, NAMVET77 said:

Now I get to see if the AC guy will put this together and put a “T” on so it can be charged like Ivan did. 

Make sure to have the switching valve wrapped with a wet rag to keep it from getting too hot while sweating on the "T".  Otherwise it may damage the mechanism.  Trust me, I speak from experience.  

Edited by Bill R
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NAMVET77

NAMVET77

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Posted

Just talked to my AC guy and he agreed to do the repair later this week. Said he knows what to do. More to follow. 
Don

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