One of my old roof top Colemans finally went south after 20 years of use. Guess I can't complain, huh? The local Camper Scalpers are quoting close to $1000 to replace this Coleman 13.5K Mach. I ordered the complete unit online for less than $500, thinking how hard can it be? Well, that is my question, "How hard is it"? I had to order the whole sheebang because Coleman said the newer model top unit is not compatible with me lower. I have removed the (3) long bolts and the lower unit. Now, is there anything, other than sealant holding the top unit on? Any other screws going into metal roof framing perhaps? Does one get out the maul to break the top unit loose from gasket and sealant or what? Please help before I get in over my head. The pros said this job takes about one hour. If it takes be four hours to save $500 bucks, I'll be pleased. Bill H, any advise appreciated as I have to keep Ron's old coach in tip-top shape and we can't tolerate a leak.
Thanks, Don

I haven't done one in a while, but if I remember correctly, it sat on a foam gasket and was held in position by four threaded rods and clamp bracket. Nothing else. I just removed the clamps and lifted it up. Your rubber foam seal may be sticking it down. The hardest part was getting it up and down the ladder to the roof. Leaks are not a real big issue, as the vent opening on the roof has a curb to prevent water from getting in.

While you have it off, check for any corrosion, treat it, and paint the aluminum where water can hide under the foam seal. I have seen metal corroded right through there.

I just changed one on our 35 and it was an original Coleman. After removing the hold down bolts I had to cut the cut the seal gasket with a knife to free the unit. I was afraid it might pull the cover material off the roof. Once I broke the seal it came off without a problem.

Get help it isn't a one person job.

ED.

Thanks Fellows;
The new unit should be on my step in a couple days and I just wanted to get all the prep done ahead of time. BTW: After dissconecting the rear unit in my 28' Regal, none of the interior lights work. Are they all on the same circuit with rear air?

Thanks,
Don

I replaced both my units this past spring. I put on Carrier V's but the installation should be the same for all units. The outside and inside parts need to come from the same vendor so the mounting holes mount up. I took down the inside plastic cover. Turned off the AC to the unit (actually unplugged the coach to be safe), disconnected the AC from unit and removed the four original bolts and dropped the complete bottom unit. Really help to have two people (some one with muscles really helps) Hardest part is getting the old unit off the roof and the new one up. Would suggest leaving it in the shipping box and sliding it up over the side. We brought my son's work van along side the barth, slid the new unit up on the roof of the van, climbed up on the van and slid the unit up to the roof. The units weight about 90lbs and can be handled better in the original shipping carton (no sharp edges). After removing the old unit, it just sits over the hole - apply steady upward pressure and it will release. Place the new unit in the same spot, align it as best you can. I placed the old unit in the shipping box and lowered it down the same way using the van. Rest of the installation can be done from the inside. Attach the new inside unit, tightened the three or four bolts, reconnect the AC and install the plastic shroud. Took us an hour for the first one and 30min for the second. One of the easier replacments items I've found.

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Russell and Donna
1988 33' Barth Regal
Gibson Exhaust, Bilsteins, ipd sway bar

An extension ladder, leaned at about 45 degrees, and a rope made it easy for two people to slide the old unit down and pull the new unit up.....One person on the roof and one inside makes for easy alignment of the flanges & seals....torque down mounting bolts in a rotating pattern...there's lots of thread travel to cause binding & bending if you don't.....My old Coleman had a sheet metal plenum that had to be cut & twisted out...New unit had a cloth plenum - nice & easy fit-up.......

...Wish all my upgrades went this easy.....

Progress Report: I just got the old 1984 unit off...it was stuck good. Using sharpen puddy knife and mallet I was able to break the old seal between the drain pan and the dense foam gasket (curb?). My Regal as no built up A/C curb other than the 3/4" thick foam gasket which was stuck to the raw sheet metal roof with a gray, hard rubber type sealant/adhesive. I'm now in the process of cleaning all the old sealant off down to the metal and plan to rough the metal up some before installing new gasket/curb. What type sealant should I use under gasket? My intentions are to take the area under the form gasket/curb to roughened bare metal, apply sealant and install 14x14" form gasket. Then caulk (what kind?) where gasket meets roof. Then clean surrounding area good and feather in new Cool Seal coat from new curb to existing, recently applied, Cool Seal coat.
I threw the old unit off the roof before I read these other easy ways to offload it. That gravity works pretty good. Am I on the right track? Hardest part was removing all the old sealant, not only from under the gasket but also around the entire upper unit pan. So, to be a little redundant, what is the very best sealant/adhesive/caulk compound which will cure into a strong water tight barrier around and under the foam gasket/curb? Someone had previously caluled aroud\nd the entire upper unit pan. Is that necessary? Seems to me, it was actually trapping water. I can think of no ration reason to caulk aroud the entire roof pan anless its for vibration/leveling contol. Your comments appreciated.
Don
'84 Regal "Barthalamew"

Don, As I recall from my swap-out, the factory supplied gasket was designed to do the job by itself. But I'm also a belt-n-suspenders guy, so I cleaned the aluminum down to bare metal and then applied a small zig-zag bead of Goop brand sealer/adhesive to set the gasket into...The relatively short tack-time of the product allowed the gasket to remain in-place while I made minor shifts in the unit's alignment, and I still got sufficient "squeeze-out" to feel like I accomplished something.....

In this application, the downsides of a silicone product seemed moot. (i.e.: dirt attraction & UV degradation)

I figure the silicone is good for 15-20 years... While there's probably "something" out there that's good for 50-100 years, sometimes ya just gotta shoot the architect and get on with the project, ya know what I mean?

The best sealant I have ever used is 3M "5200" marine caulk and sealant. If you use it, hope that the AC's last until you sell it. The "5200' is about as permanent as it gets.

I've used a lot of DAP "Dynaflex" too. A hardware store item, lots cheaper than the marine stuff. There are several grades and varieties. If you use it, get the longest rated latex-based stuff that advertises water cleanup.

There are a number of good brands in RV stores too. There's so much it can be confusing. I don't like the straight silicones any more. They let loose where you want them to stick, stick where you want them to come loose, and they won't take paint..

Don, Goop is pretty good stuff, but it can be a bear to get off. Consider 3M 4200. It is also a polyurethane, but comes off fairly easily. Do a little Googling or talk to a boat guy.

And I agree with you on sealing anywhere but the gasket. It would just be an invitation for water to collect.

None of the interior lighs work??? The AC is 110 V shore/generator. The Lights are 12v and powered by the house battery/convertor. Are you sure the house battery switch in "on"?

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Gary & Edie
North Idaho
1988 28' P-30 454

I have only one AC on my coach but would like to add another. What do you all think the chances are that the second hole, (which now has a fan in it) is wired for 120.

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The odds are pretty good that it is, but you won't know for sure until you check it out.

Dave, Years ago I installed a roof air unit on an SOB that was not wired for air at the factory (At least I don't think it was - I never found it...) At the risk of guffaws and ridicule from the group, here's what I did:

Breaker panel was in corner rear closet, which also contained the holding tank vent. Due to lack of elect. panel space, I installed another small disconnect box, properly fused, in line with main feed.....
From the disconnect box, I ran 10AWG-UF (direct-burial)wire next to the vent pipe, attaching wiring to the vent pipe with snap ties & electrical tape.

At interior ceiling, drilled a small hole into vent....another hole in vent on the exterior, about 1" above roof, and snaked wire into vent and back out of vent.....

From there, wire entered a piece of Wiremold (square metallic channel designed for service-wiring walls & ceilings - Home Depot stuff), to the a/c unit. The Wiremold was epoxied to the roof - mounted with "tabs" of expoxy so drainage would not be affected (never came loose). Sealed up the two holes in the sewer vent w/ RTV......

Result: 120v20amp dedicated line to a/c without any roof penetrations, interior holes, cabinet mods, etc.

I know, I know...the purists out there are shaking their heads...Remember, you asked!...and you didn't qualify the responses........

Thanks for all the help guys, I believe the hard part is done......all cleaned and preped.....hole temporarily sealed until the unit arrives. If PPL sends the right unit, I should to be road ready by the weekend. Have the leaves started to turn in middle TN yet?

A hardy here, hear for the suspenders and belt philosophy! My britches fall down with only a belt these days as de belly as outgrown de buttocks. Such is life in the slow lane.

CHEERS!
Don & Elle
'84 Regal "Barthalamew"