caulking around HVAC unit

[mocus]

I can only see parts of caulking sticking out between the bottom of the HVAC and roof of trailer. Beings I do not know how the HVAC is mounted on the top, I don't know if the unit is properly caulked in areas that I can't see. I would think a continuous bead would be called for? Whats say? Tom

[dznf0g]

I wouldn't. It's just a "patch" if there's a leak...and I don't think it would last with all the vibrations while running....and it just makes a mess. A proper compression gasket, maybe with sealer on the top and bottom of it, is the proper way.

[lewster]

Originally Posted by mocus

I can only see parts of caulking sticking out between the bottom of the HVAC and roof of trailer. Beings I do not know how the HVAC is mounted on the top, I don't know if the unit is properly caulked in areas that I can't see. I would think a continuous bead would be called for? Whats say? Tom

Your Penguin air conditioner (A/C) is more than likely sitting on a plastic base pan. This pan is an Airstream-only part (they are the ONLY manufacturers that use such a contraption) and it is bonded to your roof with liberal amounts of SikaFlex 221 (you can see the ooze coming out from under said base pan if you remove the lower vent/control unit from the ceiling.

The upper A/C unit is then placed on top of the base pan with double-sided tape, and the 4, 1/4-20 X 6" bolts are then screwed into the upper unit thru the lower frame to hold the entire assemble to your roof.

Just a side note: Airstream no longer uses the plastic base pan, as they tend to crack and then leak A/C condensate into the trailer instead of to the outside thru the drain hose in the wall.

IMHO, this is the most convoluted, unnecessary way to mount a roof A/C and has led to many leaking problems due to the plastic base pan. Many other OEM RV makers have been using Dometic's auxiliary drain kit to route the condensate thru the internal hose to the ground for many years……and now Airstream has finally joined the party.

So now that you know what you are looking at….what was your question?

[texascanuk]

Interesting, So they don't use the base pan anymore? I guess it wouldn't be necessary with the widebody trailers since there is not much curvature to the roof line in that area. I suppose if this owner has a leak he could remove the inner panel to access the bolts that are used to sandwich the roof line between the upper A/C body and the inner bracket. (forgive me, It's been a while since I did my install). Once those bolts are loose or off, the A/C could be lifted to get more sealant around the opening. I guess I'd have to see what's going on first.

[mocus]

I have part of my flooring rotting from just inside the door and runs about a foot toward the front of the trailer. I have been caulking every where there is a seam,, et al. I have re-caulked every seem and crack on top and that is when I noticed the crack between the AC and roof, with a few pieces of caulk visible. I have the trailer under a detached carport and have built a platform above the trailer that makes it easier to work on the roof--works most of the time.

First of all, thank you all for your responses--it gives me more of an insight as to what I will need to check.

[perryg114]

I doubt it is the AC leaking to be that far forward. The way these things are built is that any water that leaks between the front door and the corners will either drain out at the corners or at the door frame area. I found a leak in the window frame where the seal between the glass and frame went bad and also some leaking rivets just to the right and above the door. I also found some loose rivets near the bottom of the door frame. Rivets around the door leak because the door is constantly being opened and shut and it loosens the rivets.

Perry

[Hodum]

I removed and replaced the original air conditioner from my '95 model and I can assure you that it was not only sealed well, but the sealant was so adhesive that the hardest part of the job was removing the old unit. I think it would have stayed up there if there was no bolts involved. I simply used the rubber gasket supplied with the new unit with no sealant whatsoever (as per instructions) and have had no problems with leaks.

[dznf0g]

So when did AS quit using the pan? Mine has a black narrow tray in between the plenum and the interior cover. I can't see a pan between the roof and the A/C unit.

[lewster]

I started to notice them in 2012 model year, but I'm not sure of the conception date.