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AC Puzzled
#1

Hoping that someone has had the same problem and got it figured out.
I am about to leave newell after they had tried to fix the problem for a day and a half. 
My front ac unit was only putting out 61 degree air but would run.
Newell determined that I needed a new compressor so went ahead with that which also included a new drier and capacitor.
So after the new install of compressor the unit started and got cold but within a few minutes the fan would quit then the compressor would overheat and shut down. So went inside to the electrical box by the condenser and found a capacitor that looked like it blew up, the top had pushed up and oil had leaked out, so that was replaced and same problem exist.
Then the fellow checked out the thermostat and that checked out ok. He was not very familiar with all the stuff inside the box so after a day and a half and now Newell has closed for the 4th we decided to call it quits. We don't want to hang around for 5 days 
and need to get back to our trip. figuring we were going to get a large bill for basically nothing we were told there was no charge.
We were happy with that but we now have no ac on the front of the unit. 
Remember the AC unit was working ok but blowing only blowing 60 degree and now the problem is the fan on the compressor unit comes on for a few minutes then shuts off which allows the compressor to over heat and shut down.

Any help would be appreciated. Happy fourth.

Brad

1988 40 ft 8v92 newell
Coach name Big Blue
25 ft Haulmark car hauler with Andersen Anti sway
2012 Toyota FJ Cruiser.
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#2

Brad,

Dometic, correct?

How comfortable are you with electricity? If not familiar with safe practices, then don't go into the live circuits.

My first guess would be that, the fan was miswired during the work. Look at the schematic on the panel and check the wiring for the condenser fan motor against that wiring, especially the wiring going into and out of the start/run capacitor.

The capacitor that you replaced inside the coach is for the evaporator unit, so I am not surprised that it had no effect on the problem.

How much current is the fan drawing? Can you clamp your ammeter on one of the leads to the fan?

Those fans are notorious for failing, but the failure is almost always that the bushings wear and the fan won't start.

The second guess is really a wild guess, but the best I remember that fan start circuit has a really old school thermal interrupt that takes the start cap out of the picture. It is a round black device about 1 inch long and 3/4 inch around, as best as I remember.

I am just really trying to think about things that would allow the motor to start but to overheat after running.

And I wouldn't hesitate to put a new run capacitor on the fan motor. You can test the capacitor with a analog volt meter if you think it's the culprit.

When you say it shuts down, what shuts down? Blows breaker? Compressor shuts off? Something else?

My phone is 817 223 2056.

Richard and Rhonda Entrekin
99 Newell, 512
Maverick Hybrid Toad
Inverness, FL (when we're home Cool )
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#3

On the road will answer mor in-depth tonight.
Brad

1988 40 ft 8v92 newell
Coach name Big Blue
25 ft Haulmark car hauler with Andersen Anti sway
2012 Toyota FJ Cruiser.
Reply
#4

I am comfortable with playing around with the stuff.
I won't be able to get at the unit till get back in NH, a week or so. But I would think if the fan was wired wrong would it even work? The current stays around 2+ amps and does not jump up just before the unit quits.
The guy at newell working on the unit said the start run capacitor either works or it don't, not start then quit.
When I start the unit the inside fan comes on as it should then about 2 minutes later the compressor AND fan come on together
which runs about 5 minutes making cold air but then the fan quits then in about a minute the compressor will draw as much as 50 amps the get hot and tthe temp overload sensor on the compressor shuts everything down except for the fan inside the coach.

Now today while traveling I tried leaving the switch on to see what would happen.. The unit ran about 5 minutes then shut off then after about 3to 5 minutes would come back on and do this over and over. So it looks to me like the temp sensor on the compressor senses when the compressor has cooled enough to restart then it restarts. But the fan quits again etc etc.

It almost makse sense that there is a fan control that is malfunctioning and it is probably in the box in the coach but I don't know enough to know what to look for. I did hit the different whatever they are/serve with a infrared thermometer (great tool) and one item was reading just over 100 degrees. I will attempt to add a couple pics and you will see what I mean. The hot item is at the top right about 3/4 dia and white. You will note in the other pic the capacitor that over heated which was replaced.
       
Brad

1988 40 ft 8v92 newell
Coach name Big Blue
25 ft Haulmark car hauler with Andersen Anti sway
2012 Toyota FJ Cruiser.
Reply
#5

The good thing is that the problem is regular and repeatable.

On top of the air handler unit inside is a small silver box, usually covered with a rubber bungie cord. The control circuit board is in there. I don't remember if there is a schematic on the cover of the box or not.

But I would start at the circuit board and find the voltage that runs the condenser fan. Hold the voltmeter leads on that until the fan quits. If you still have power to the fan from the control board then go to the outside unit.

Keep tracing the electricity path to the fan motor until you find where the fault is. I do not believe the fan motor has a thermal overload like the compressor does.

Richard and Rhonda Entrekin
99 Newell, 512
Maverick Hybrid Toad
Inverness, FL (when we're home Cool )
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#6

In the pic is the inside of the box you speak of. I don't see a circuit board.

1988 40 ft 8v92 newell
Coach name Big Blue
25 ft Haulmark car hauler with Andersen Anti sway
2012 Toyota FJ Cruiser.
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#7

I was able to download a schematic Dometic. Will try to find where I put it & post it here.
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#8

    This might help

Forest & Cindy Olivier
1987 log cabin
2011 Roadtrek C210P
PO 1999 Foretravel 36'
1998 Newell 45' #486 

1993 Newell 39' #337 
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#9

.pdf 3101321.036 Duotherm AC.pdf Size: 198.94 KB  Downloads: 35

Here is the manual I had downloaded.
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#10

Thanks guys for the schematic. 
It should help when I get inside the box with my meter.
I might even send a copy to Newell. They thought they had one but none was found.
Does anyone know if item 26 would be the time delay for the fan in question. Seems like it to me.
And if so where would I get one?

Brad

1988 40 ft 8v92 newell
Coach name Big Blue
25 ft Haulmark car hauler with Andersen Anti sway
2012 Toyota FJ Cruiser.
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