Replacing TT AC

[rfloyd99]

I have to replace the rooftop part of my four year old Dometic AC. It went out last Summer and I'm just now getting around to it. Back then I did some research and it seemed there were several places to buy one, at around $475-500.

I plan to do the work myself. I'm pretty handy, but not a pro. An RV tech told me it was a fairly simple job.

Anybody have experience with this? Advice on where to buy, is used an option, installation tips, etc. would be greatly appreciated.

[DFord]

I can't imagine why no one has told you the truth here. That's the compressor in the picture and those are the wiring terminals! The wires are stuck on the terminals with spade connectors. I'd try to pull them off and then "ohm out" the compressor to see if it's shorted or open. If it ohms out correctly, I'd clean up the terminals and re-attach the wires.

The wire from the "Klixon" (overload) to the "Common" terminal on your compressor is burned up. The terminals are called "Common" - "Start" - "Run". Clockwise from the terminal that's burnt.

If the compressor ohms out okay, I'd try replacing the Klixon and the capacitors to see if the compressor will run before scraping out the whole thing.

https://www.wikihow.com/images/thumb/6/6a/Check-an-AC-Compressor-Step-10.jpg/aid9606691-v4-728px-Che... (After viewing this image, use the "back button" on your browser to return to this message.}

I borrowed this image and text from this link: https://www.wikihow.com/Check-an-AC-Compressor
Purchase a multimeter and set it to continuity. There should be a dial on the front of your multimeter. Set this dial to continuity so that you can test each individual terminal to determine where the fault is. Continuity tests whether there is an electrical flow between the terminals. If there is no flow, it’s likely that the terminal is broken or damaged.

If you can get the numbers off the Klixon, you can get a replacement online. Local suppliers are usually reluctant to sell to the customer.

The Klixon is attached to the COMMON Terminal.
The White wire is on the RUN terminal.
The Red wire is on the START terminal.

[rfloyd99]

Click For Full-Size Image.

I'm trying to post a photo, hope this works!?!

[rfloyd99]

DFord, the model # is B57915.71X.

I have pictures, I can easily text or email them to you, if you PM me your info. I'm sure I can figure out how to post them, but not for an hour or so. It looks like there is plenty of room to hang a bypass as you suggest. One of the terminals looks pretty burned, but may be salvageable.

I am in Clearwater, (St Pete/Tampa Bay area).

Thanks to all for the suggestions!

[steveh27]

I replaced mine with the Dometic High Efficiency unit for about the same price. It uses less power and can be run with a Honda 2000 if needed.

[sayoung]

DFord wrote:
Do you know the model number on your Dometic air conditioner? I've been repairing air conditioners since 1966 and can't imagine a non-replaceable run capacitor. I'd like to look into that some more. Unless the terminals are burnt off the compressor, seems like you'd be able to hang a run capacitor in there somewhere and bypass the original even if it wasn't removable. Any way you could post a picture?

Where are you located? I'm just south of Miami right now.

I started the summer of 65.
I also can't get my head around an irreplaceable run capacitor. Even if " true ", any AC tech worth a flip should be able to work around that if the compressor wiring near the terminals is accessible...

[DFord]

Do you know the model number on your Dometic air conditioner? I've been repairing air conditioners since 1966 and can't imagine a non-replaceable run capacitor. I'd like to look into that some more. Unless the terminals are burnt off the compressor, seems like you'd be able to hang a run capacitor in there somewhere and bypass the original even if it wasn't removable. Any way you could post a picture?

Where are you located? I'm just south of Miami right now.

[rfloyd99]

Matt, thanks for the suggestion, I plan to look into that.

I talked to one place that was a Dometic warranty station. The person was nice, but said they couldn't even look at it for a quick diagnosis for three weeks. He was very helpful and took time to answer several questions. He said it sounded like one of the two capacitors failed. One is a replaceable part, the other is not. He predicted only a 30% chance that it was the replaceable one.

I took it to a large RV dealership service department, the tech went right to the problem and said it wasn't a replaceable part. There are two similar looking electrical components at the top of the compressor (easily accessible). On one of them there was a short, I guess, that burned the wire off of its terminal. The two components were covered by a heavy plastic cap to shield/insulate them, so I don't see how there could have been a short, or anything else that caused the little fire that melted the wire.

It looks like the terminal is damaged, but maybe somehow the wire could be reattached. But I don't know what the underlying cause was, so perhaps more is needed than just reattaching the wire. I have photos of this, if anyone would like to see them.

Thanks for your response, I really can't afford the cost of replacement, but have to fix this before our trip this Summer.

[ScottG]

Wow, hadn't heard of that. Pretty crummy on their part.
Best of luck to you!

Scott

[Matt_Colie]

Rfloyd,

Not being a replaceable part means one of two things:
The manufacturer does not supply an identical part to replace it.
OR
The failed part is buried in an assembly that make replacement very difficult.

Neither of these is a reason to scrap the entire unit. Do you have a friend (or even a friend of a friend) that is an electric or HVAC smart person??
Offer said something of moderate value (dinner or glass encased substance) to look at the unit and see if he has an idea.

Capacitors are nothing special. It pretty much has to be external to the refrigerant circuit, but it might be a physical problem that needs a creative solution.

I am distressed that Domentic doesn't want to help you, but that is their choice. Oh, and when you get this figured out, sell the plan. There is nothing that they can legally do to stop you from selling a repair part that they will not supply.

Matt

[rfloyd99]

ScottG, after owning the trailer (bought new) 3.5 years with only moderate AC use, a capacitor failed. Dometic's genius designers made this a non-replaceable part, so the entire unit must be replaced.

We were sitting in an RV park with the AC running on day two of a long trip, when I smelled that "electrical fire" smell. The fan continued to work, but no cold air. As far as I know, there was no cause other than poor design, or poor workmanship at the factory. I use a surge protector, so I doubt there was a problem with the power.

I sent a long email to Dometic, hoping they would offer something toward repair since this was a no-moving-part item that shouldn't have failed with so little age or use.

Of course, their response was basically "too bad".

[Mike134]

etrailer.com has good pricing on stuff I've bought. have not searched for an A/C however

[ScottG]

Just curious, why do you need to replace it?

[rfloyd99]

OP here. Before posting I did a search but didn't try too hard. After posting I searched better and found a recent post on this issue which answered most questions.

But, anyone have ideas on best place to buy this expensive item? Is there a place that sells used or reconditioned ones?