Repair of Airxcel 8333B676 AC roof unit

Window A/C units are also sealed systems. So are Fridges, Freezers, Water Coolers, etc. They use a tiny "cap tube" to control refrigerant expansion. Dislodge any impurity and you clog the cap tube. They also hold only a very small refrigerant charge. Just a little too much or too little and it doesn't work right.
There are "bullet valves" that clamp to the tubing but they leak. And officially the refrigerant's supposed to be "recovered" using a specialized machine. Then "evacuated" with a vacuum pump before charging. Combine all these and you get a non-repairable unit, at least practically.

The 13500 Coleman (now RVP) Mach A/C on our 1984 Class C was working fine when we sold it in 2009. It wasn't cooling well in the last season or two we had it, so I did the Chris Bryant tune-up and it went back to COLD. The RVP Mach 15000 on our 2002 coach is working fine.

The Coleman/RVP units last a long time. Failures are typically Dirt, Capacitors, and the Shroud's made of Eggshell. MaXXair has their TuffMaxx replacement shroud, lifetime warranty.

Just curious - what is the average lifespan of these units (assuming one does not damage the unit as I did LOL)?

It appears that RV roof AC units, unlike a home unit, are built to be un-repairable if they need a re charge.

A home unit is a side draft, and a rooftop is a down draft. I have never seen a residential unit with a down draft....maybe someone else has. Also, the drain location may be a problem.

On another note, I am also considering buying a new unit and installing it myself. Anyone have any recommendations as to how to get the new unit up there, without a hoist? I was thinking of building a ramp out of 2 x 8's or something like that - wondered if anyone here has ever done this and what method they used thanks.

Oh no... I am not suggesting that a window unit would be installed in one of our RV windows - that would be silly :) Also the roof unit would not be repaired while on the roof, I am taking it off of the RV roof prior to repair.

I had to do some bending of sheet metal to get the casing back into shape and there is very little difference I could see between a home window unit AC and an RV roof AC. All that is in the internal housing of the Coleman RV unit is some very thin - maybe half inch to an inch thick fiberglass insulation. That and some foil tape would do the job.

The fabrication to replace an RV "RTAC" (Roof Top Air Conditioner) in the same location on the roof would be prohibitive. The RTAC also offers a degree of protection from the elements that a room unit does not.

Installing a room unit, meant for a residential window, in an RV-type window would also not be easy. And you need to have a power outlet there. And it needs to be solid enough to not fall out onto the road.

A punctured RTAC sounds like it might be an insurance claim.

But beyond that, get a new RTAC.

Belated thanks for the above it's been almost a year LOL, looking into this again before vacation season.

What about buying a window AC? I'm sure the guts are the same it's just about the mounting. Has anyone ever done it this way? It would be a lot cheaper - it seems to me from my conversation with a few places last year, there is little difference between a window AC and an RV AC - they both run off of 120 and are about the same power. One can get a window AC brand new for 200 to 300 bucks or less.

It isn't just a simple weld job. Once the tube is repaired you have to replace the refrigerant and that is the problem. The ACs are sealed units. If you add a service tap you have destroyed the integrity of the whole sealed unit. I see you are in Michigan but you don't say where. We are fairly close to Elkhart and I would just look there for an AC. They are not that difficult to change yourself. A foam gasket, 4 long bolts, and an electric connection are the only things to do. The AC will come off from the roof side after you remove the inside covers and the 4 bolts. The biggest problem for me is the roof is too high. I don't do ladders or heights. I had one repaired one time and it did work but if the fellow hadn't been a friend it would have been about as expensive as a replacement. Check out PPL and some of the other online parts suppliers.

Many times our roof AC's don't have the ports to recharge the unit. They can be added but by the time you repair the leak, install and recharge the system, your most of the way towards what it would have cost to replace the whole thing.
I you live someplace where things are more reasonable then the price may be lower but if you live where I do, it wouldn't be worth it.