Water from the roof AC

[AJMike]

During the summer we make a trip from southern Arizona to South Padre Island in Texas and each time we have made this trip with our current RV we have found water leaking from the roof AC onto the bed and floor of the RV. It is leaking from the inside cover under the AC and the AC in this RV is NOT ducted, so it is coming directly from the AC unit itself which is right above the foot of the bed.

The first time we saw this it was raining and I thought that it might be rain water getting inside the AC cowling but during the second trip it was not raining and we still found water leaking. When I checked the outside of the RV I saw a lot of water coming down the outside of the RV so clearly some of the water that the AC removes from the air is being discharged outside of the RV, but not all of it.

This only happened when we got into central and southern Texas where the humidity is relatively high, and we never saw it when we ran the AC here in Arizona or in New Mexico or Utah, so I now assume it is condensation due to the high humidity and/or water that an AC removes from the air, so I have a couple of questions.

First, is this common? We have never seen it in any of our other RVs, even when in high humidity areas.

Second, of course, is how to stop it. Our local RV repair shop tells me that it is fairly common and due to some manufacturers not installing a way to remove the excess condensation, so if there is no built-in way to remove the water how can I do that? Do they make pump kits to remove this water from the inside vent cover? If so, where?

[JohnBike]

While this is happening, check the roof. Condensate should be running out from under the AC cover toward the drain rail. Pop the cover and check the condenser fins/coils. There should be a tray of some sort that collects the condensation. Find out where the condensate drains. I would bet a few $$ that there is a piece of tubing from the drain tray that was either missing or not routed under the cover. Worst, of course, is no drain tray at all. It happens when the dude assembling the AC unit takes a lunch break and the drain stuff is the last piece to be assembled.

[DancinCampers]

The roof unit should have a plastic tray located at the bottom of the indoor coil to catch the water. This tray will extend outside the enclosure housing that covers the indoor coil. There should be a plastic mesh screen located in the tray where it passes thru this housing (to keep out bugs). Remove the units cover and see if this screen is plugged up with slime. In our unit we have a condensate pump located in the tray which pumps the water to the bottom of the rear passenger corner of the coach. If this screen is plugged up then maybe the increase in condensate due to moving into a higher humidity area is not able to pass thru the screen fast enough.

[Old-Biscuit]

Basic RV Roof AC Unit Components




Condensate drip tray directly under the Evap Coil collects condensation and drains it out onto roof via drain holes
Drain holes are small and get slimy -- clogged so drainage is obstructed so built up condensation will drip out of the ceiling vent (return air side)

Need to go on roof & remove shroud
Under the shroud will be a sealed cover over the return air side/Evap Coil
Need to clean drip tray/drain holes and I would enlarge them using a drill bit (I enlarged mine to 1/4" holes)

All condensation should collect in drip tray and drain out onto roof...not inside the RV

[johnhicks]

Clean drain holes and make sure they aren't otherwise obstructed.

Tighten a/c mounting bolts a few turns, compressing the gasket more.

Replace a/c gasket.

[AJMike]

This gives me some hope. I had thought that the problem was something serious but these posts make me think that perhaps it is something that can be fixed without too much trouble.

Thanks to all for the help. And I am especially grateful to @Old-Buscuit for the diagram. It is not as complex as I thought it would be.

[craigd853]

Originally Posted by AJMike

This gives me some hope. I had thought that the problem was something serious but these posts make me think that perhaps it is something that can be fixed without too much trouble.

Thanks to all for the help. And I am especially grateful to @Old-Buscuit for the diagram. It is not as complex as I thought it would be.

Hello, also make sure your evaporator is clean and your prefilter was cleaned or changed as well. If either is dirty the evaporator can freeze up and when it thaws out is will produce the water on the inside of the a/c that you are experiencing. Like others have said it is important to make sure the drain is free and clear of debris and that the a/c is not leaking around the gasket on the top of the rv. Good Luck

[Isaac-1]

I am not real clear on your description, but I did want to note that it may be that condensation is forming on your vents and dropping from there. I have this issue on my ducted air condition where the metal vent registers will get cold enough for condensation for form directly on them and drip.

[Coarsegold]

I had almost the same issue and after we pulled the AC unit it was found that when the AC unit was installed at the factory a screw that was too long went into the roof membrane and allowed condensation to leak in.

This is a rather rare thing but shows that all it takes is one small mistake like a small puncture or seam to make a big mess.

[DFord]

While this is happening, take off the cover inside so you can see exactly where the water is coming from to start with. The fan draws the air through the indoor coil but there could be something preventing the condensate from following the coil's fins down into the condensate pan. You should be able to see if the water is coming over the lip of the condensate pan meaning you need to clean the drain holes so pan can't fill to overflowing. To clean the drain holes, follow Old Biscuit's advance about taking the cover off the air conditioner and then taking the cover off the indoor coil.