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2.7 · 08-11-2016, 12:52 PM

We are replacing the A/C in our '71 International Ambassador 29 foot trailer. The shroud is basically gone and the compressor needs replacing. We can't see putting the money in to fixing and replacing those when we could just get a new unit.

We are looking at a Dometic and also at a Coleman. Both units are 15,000 BTU. The Dometic upper unit has a weight of 76 lbs and the Coleman upper unit 110 lbs. Will either of these units require any strengthening of the shell/roof of the trailer prior to installation? We have no idea what the weight of the current unit is.

HiJoeSilver · 08-11-2016, 10:44 PM

Depends. As long as you have cross ribs supporting it fore and aft of the ac hole you should be fine.

TheGreatleys · 08-12-2016, 04:26 AM

Mine was fine without additional structural support. There are ribs on either side. You do need to frame out the hole so the mounting hardware has something to grab on to. The old Armstrong unit uses about 100 screws and a gallon of Vulkem to attach to the roof, but the Coleman and Dometic models pinch the roof and compress a gasket to seal. I used square aluminum tube but most people use wood.

HiJoeSilver · 08-13-2016, 09:27 AM

Quote:

Originally Posted by TheGreatleys

Mine was fine without additional structural support. There are ribs on either side.

You need to be sure you have ribs fore and aft of the hole that the ac will rest on. Can't rely on the reinforcing brackets that run length wise down the sides of the center top skin panel. Without at least ribs fore and aft of the hole the weight of the ac will cause the outer skin to bow in under the weight causing problems down the road.
As long as you have cross ribs, the roof will support both ac's.
As mentioned by thegreatleys, you have to frame around the 14" hole so the ac has something to clamp down on when tightening the bolts. Some 1x wood works well. There was probably some blocking there from the previous install you can reuse.

TheGreatleys · 08-13-2016, 09:57 AM

Quote:

Originally Posted by HiJoeSilver

You need to be sure you have ribs fore and aft of the hole that the ac will rest on.

I would think that since OP is replacing an existing AC, it's a pretty sure bet there is sufficient factory support to hold an AC in that spot.

crestonrv · 08-13-2016, 11:37 AM

u can get new pan for dometic penguin , not for coleman .
shoud be drain tube in ceiling /wall . comes out forward of wheel well .
if no pan needs support at from as opening is 1.25" shy of hoop/rafter and seal on a/c will depress there and create bird bath ( water trap )
ood carries pans 100.00 none avail for brisk air or coleman though I did hear somewhere that andy out at inland rv was making a pan for a coleman ? check befor u buy.

Lumatic · 08-13-2016, 11:50 AM

I had a 13.5 Dometic Penguin installed on my 71 Tradewinds. The opening was reinforced with a 2x4 frame.

You might want to check out the interior noise levels from the various models.

Don't trash the Armstrong. Somebody on the Forums might be interested.

HiJoeSilver · 08-13-2016, 12:25 PM

Quote:

Originally Posted by TheGreatleys

I would think that since OP is replacing an existing AC, it's a pretty sure bet there is sufficient factory support to hold an AC in that spot.

Not necessarily. My 23 had a original factory installed ac. There was one cross rib forward of the opening. The next cross rib was, off the top of my head, about 42" back from the back of the opening, so the entire aft weight of the ac sat on unsupported metal, deflected the metal in and caused cracks in the shell metal where the ac drain pan rested.
I had to make 3 patches to seal and reinforce the cracks, and made some metal brackets to act as ribs to transfer the weight out to the sides and across the center span.

loechli · 08-13-2016, 12:44 PM

We replaced our original AC on our 1972 International and did not need any extra bracing. I chose the Dometic as it was the lowest profile and looked the best on top of the trailer.

We had it installed at the factory in Jackson Center, as there were tons of rivet to remove then replace.

Steve

tlavergne · 08-13-2016, 01:12 PM

We just replaced the AC unit on our 1978 Ambassador. We went with Dometic 15,000 BTU. Nice unit, quieter than the old Armstrong. Very happy I didn't rebuild Armstrong and went new.

SuzyHomemakr · 08-14-2016, 01:21 PM

Just recently had the entire upper unit of my Dometic replaced under manufacturer's warranty. A month before it expired! My old Armstrong was very dependable until it wasn't. Dometic is having all kinds of problems with these foreign-assembled units. Now my NEW Dometic is still tripping the breaker occasionally. It's still just as loud as the old Armstrong. I've had to install another A/C to be able to keep up with the Florida heat, even though it's the biggest that they make.

I wished that I'd listened to those wiser than myself, and found a place to rebuild the Armstrong!

silvercomet · 08-15-2016, 07:06 AM

Rebuild point of view -
I purchased my 1972 Safari in 1999 and in 2003 partially restored the original AC unit. 27 years of service was amazing! Based upon the cost of a new AC unit and the reliability issues that I had read about, I thought it was worth risking a rebuild. Additionally, I didn't have to do any frame modifications and the drip line would continue to work. I replaced the compressor, shroud and starter capacitors. I cleaned up the fan motor only. I actually didn't much more than "google" and order parts. I called my home AC repair guy and told the receptionist what I wanted done. She replied "we don't work on RVs". So I waited 3 days and called back and said my AC isn't working and need a tech to come to my house. When he arrived (smile), I had the ladder on the AS and told him I needed the compressor replaced with the new one I had purchased. He was done in about an hour. Inland RV shipped the new shroud to my front door and I installed it. It's August 2016 and it blows ice cubes. To be fair, we use our AS for vacations and the longest time I've run the AC continuously is 2 weeks. I think will again replace the parts when needed. The old units lack some of the fancy options, kinda noisy, but they are tough. The older I get, the more I like older stuff. Good luck!

2.7 · 08-15-2016, 08:59 AM

Thanks everyone for the input. We actually got it going this weekend. An AC guy told us last week the compressor needed replacing.

We got up on the roof and opened the shroud. Inside was a dead squirrel, a huge squirrel nest that looked like it was constructed from an old tarp and fibrous materials. Also pecans and lots of decaying tree matter. Needless to say all of this was preventing the fan from running. We cleaned it all up and the AC blows cold now. The compressor does cycle though, so we will hopefully just need to get the freon level topped off.