AC leaking when running combined with heavy rain

You could tighten the AC unit mounting bolts as the gasket may have settled.
Make of AC unit?

Don't over tighten the 4 bolts as this will crush the gasket. Tighten no moe than one fill turn on each.

If this does not stop the leaking, you will need to remove the a/C unit and replace the gasket. DO NOT caulk the gasket. The gasket should not be tighten more than what it takes to compress the gasket by 1/2. Tighten all 4 bolts equally.

Ken

First, is water leaking in, or is it condensing inside the unit and dripping? When mine starts that I open a high window, and rig a fan to blow out. Normally stops fairly soon.

Thanks all, appreciate the input. I have never removed the AC unit so will spend some time googling that and give it a go with a friend to see if that fixes it.

@enblethen - it's a Coleman Mach 1

TXiceman is correct to a point. Coleman units have four bolts. They have a spring around the bolts to keep unit tight as the gasket compresses. You have to urn bolts like 4-? turns so snug it up.
Bolts are accessed from the interior of the rig by removing ceiling unit.

You're not removing the AC. You are just removing the 4 screws holding the panel up on the ceiling inside the trailer. Once the panel is down you should see the four bolts that go straight up through the roof.

An actual mobile tech, with just basic knowledge, should have already viewed existing gasket, snugged bolts if needed, or suggested replacing the gasket.

Often times an RV that is just a few years old will need bolts snugged up. If you install a new gasket, snug it properly, it too will likely need a bit more tightening, after a couple years of towing, and vibration.

Jerry

If you take the inside cover off to get to the bolts, you will likely see how the warm, moist air from the intake can contact the cold surfaces.
Maybe next rain, drop the cover, find source of water?


Lazy man idea about re-installing the 4 bolts; (Young person may have no issue, but many in my age group have problems working overhead) They are long, for diameter, and not a lot to guide the top end to hole. And while you are trying to get them started, you are holding the plate up and in place. I took a couple pieces of all-thread (1/4-20, IIRC) longer than bolts, screwed them into holes. Much easier to start nuts, and the studs hold plate up while start 2 bolts. Double nut to remove studs, replace with bolts

Lots of jumping around here. Stay on diagnosing for a sec.
Have you been in a heavy rainstorm without the AC running? Does it still leak? Did you try to make it leak with a garden hose spraying the roof/aC?
Because if it’s an external leak (gasket likely or possibly a thing else idk what) that should have nothing to do with whether the aC is running or not. It can’t suck in the rain as it doesn’t pull outside air in.
But as mentioned it’s possible it’s just condensation from being 105deg and 169% humidity lol.
But yes the most likely leak location is around the gasket. Either too loose, over squished or maybe it’s rolled or pinched. Could a been like that since new.

@Grit Dog: So the issue being I am just there on weekends so coordinating me being there during rain is not always accessible but trying so I can take a look. So far I have only seen it leak during Rain with AC on. With AC off I did not see any water coming down, but it does not mean that it was not. I say this being it seems water has followed along one of the ceiling panel tracks to the wall above my slide. It looks fairly early on still but I have detected some moisture there now. So the drip could be along the seal and only visible when AC runs being it pushes some out of the grates making it visible. This issue still looks fairly new based on what I can assess so far.

@all - can I drill a small 1" hole in the ceiling panel close to slide to get inspection camera up there without damaging anything? I have some moisture now to deal with and I expect a fall service.