Raising A/C on roof

[Thurman]

Not sure if this is the place to post this, but here goes: I had a new A/C put on my '05 FR last March (2013). During the very first rain after this installation I went out to look for any leaks. There was a fast drip of water coming from the interior cover for the A/C. I called the local RV repair center and told them this so they asked me to bring it back for them to check things. They replaced the foam seal between the A/C and the roof and stated that the original had become crooked during the initial installation. Some months later while camping there was a very heavy rain storm that lasted almost all night. Sure enough water came in dripping from the interior cover for the A/C. I removed the cover right then and saw water intruding beneath the bottom of the foam gasket. Another call to the RV center and I was told that the first seal replacement was free, any other would be at my cost. I was not happy with that but knew I would never change their minds. So myself and a friend (great help) replaced the seal under the A/C unit. Funny thing we noticed was that the seal the RV center had put on was sort of wadded up in two places. Just a bad job IMO. I had read somewhere about a guy who had leaks between this seal and had replaced his seal multiple times. One thing he found out was that there was a "droopy" place on the roof behind the A/C attributed to the weight of the A/C unit and it bouncing as the camper went down the road. Mine also has a droopy place behind the seal area of the A/C. His solution was to remove the A/C unit, then make sure that the rubber roofing material was not glued from the edge of the open hole and going back about 2 1/2". He used a wooden paint stir stick for a 5 gallon paint bucket to assure that the roofing material was not glued to the plywood back the desired 2 1/2". He rounded the end of the stir stick so it would pierce the rubber roofing material also. The he made spacers from 1/4" thick wood to place under the roofing material. One side of these spacers were cut on a 45 degree angle, then sanded on all edges. He placed these wooden spacers under the rubber roofing and on top of the plywood the roofing had been glued to. This gave a raised "pedestal" area to mount the A/C unit to. This is what I did today to raise the mounting surface for my unit. One thing for sure- -when I removed the A/C unit there was clear evidence that water had intruded between the rubber roofing material and the foam seal for the A/C unit. And YES the A/C unit had been properly tightened down. When I started this task I climbed up my ladder until I could see across the roof of the unit. The A/C was sitting practically right on the top of the camper. After completing this task there is a good 3/8" of clearance (1/4" spacers + the new foam gasket) between the bottom of the A/C unit and the roof. I may be completely wrong on this but the way I see it now water would have to puddle up at least 3/8" high in order to get between the roof material and the foam gasket. I also added spacers under the back of the A/C unit to keep it level to the roof. My next project involves making something to attach to the water trough under the evaporator so that the water does not run out onto the roof. I'm wanting to route the water to the back of the camper then out onto the ground. Hopefully this should eliminate the water run-off from the evaporator going out all over the roof and also eliminate the mold/mildew type stuff near the A/C unit.

[BBQin]

I think that's a great idea. Often times mass manufactured vehicles, and even homes, arent put together the correct way. They're slapped together that makes them look good and works for a while but eventually it fails. A little time and ingenuity can always improve a mass-produced product. I'll be pulling the AC on my TT and will probably steal your ideas when it comes to replacing it. You dont happen to have any pics of it do you?

[Thurman]

"BBQin"- -Sorry to say I only took one photo and that photo shows the water passages where water had clearly gotten under the foam gasket for the A/C. The temp down here that day was in the high 70's and I had my "get-er-done" attitude on and didn't even think about photos. I will do my best to draw up something understandable as to how I did this. Then I will post the instructions along with the water trails photo. I think I have to put the drawings into a file and post a link to the file. I know someone who knows more about doing than I do. It may sound strange but I'm just waiting for a good rain here now. I've got the TT really level and I'm actually going to go out while it's raining to see how the water on top of my TT travels.

[Thurman]

"BBQin" and others: Hopefully this drawing will show how I did the "pedestal" for my A/C unit. I used pieces of 3/8" thick x 4" wide x 24" long red oak from Lowe's. The angle cut on these pieces of wood was not calculated. I just drew the lines onto the wood and used a table saw to cut the angle. I did not glue the pieces of wood to the plywood under the rubber roofing nor to the rubber roofing itself. I'm betting the weight of the A/C and tightening the seal down will hold the boards into place. Pay attention to "Smooth all edges". The last thing I want is for the board to put a hole in the roofing material. The photo shows what I believe to be water intrusion under foam seal. The pollen in this area seems to have added some color to the water so the leak(s) can be seen easier. It has been raining here since about 6 o'clock this A.M. I set my camper tilted just a bit high in the front yesterday so water would run off easier. I went out this morning, climbed up the stepladder so I could see across the top of the unit. When the water traveling across the top of the unit got to the pedestal it would not try to climb up the pedestal, it went around the pedestal. That is what I wanted to see. NO leakage in the camper either. I hope this helps someone else.

[BBQin]

Makes sense to me. Any issues with raising the unit up that much? I was concerned that the plastic trim piece inside may be an issue.

[Thurman]

The plastic trim piece inside was no problem, and I have the ducted version A/C. If you think about this you are actually raising the A/C unit the 3/8" thickness of the wood. The bolts for tightening the A/C unit to the TT, on mine at least, are probably a good 8" long. I've always wondered why they are so long. One thing I forgot to put on the drawing was that I put the longer pieces of wood into place first making sure I had them centered with the 14" x 14" opening, then placed the shorter (the 14" pieces) into place last. That way when I butted the 14" pieces up to the longer pieces it formed a near-perfect 14" x 14" opening. It's still raining really good here but I went out this morning with an umbrella to look at the top of the TT and everything looked well. NO leak so far inside the TT. Maybe I did something right this time