Rooftop Air Dripping During Heavy Rain but Only When Running

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wae

wae

Well-known member
Joined
Jun 3, 2016
Posts
108
Location
Northern Kentucky
I have a Dometic Brisk Air II rooftop unit that I installed about a year ago.  We've had super heavy rains this year and not a drop of water has come through the unit when it isn't operating.  When the unit is on, however, it will make a gurgling noise and as soon as I turn off the fan, water pours out of the air return vent on the bottom of the unit by the controls.  If you don't catch it in time, it seems like the water builds up to where the fan can't keep it away and it starts to drip out that same spot.  Turn off the unit, however, and once you dry out what was already there, the leak stops completely.  Both times this happened, I wasn't able to take the time to investigate too closely, and I've got a stupid boot on right now because of a broken toe so I can't climb up top right now.  My guess, however, is that somehow because the heavy rains happened when it wasn't all that hot outside that I may have been icing up the coils or collecting a large amount of condensate that it can't drain quickly enough.  Does it sound like I'm on the right track or is there something else I should be looking at?  Even during absolutely torrential downpours, there is not a drop of water coming in anywhere when the unit isn't running so I can't imagine that there's a roof leak causing this, but I'm open to any possibility!
 
Sounds to me like the drain holes on the top unit are plugged, and the AC water has no place to go.  I would get up on top, take off AC shroud, and clear the drain holes.  If that is not an option, I would call a mobile mechanic. You can end up with much more problems if you continue to operate as is.
 
Just open up the inside cover and tighten the 4 screws up.
 
This doesn't sound like a mounting bolt failure. More likely it is a restriction of water flow from normal condensation. The drain system for condensation is separate from the barrier that keeps rain water out.

If you are unable to get up on the roof, find someone that is and is able to take the shroud off to have a look and resolve the issue. Leaves, vegetation, bacteria, algae are pretty common causes of condensation drain issues.
 
  It's nothing to do with a mounting bolt failure, it's just re-tightening the unit down to seal on the mounting gasket.

(IMO)  >>    The mounting/sealing gasket the unit sits on settles in with age,vibrations and or the mounting screws on the unit may have loosened up with all the bouncing going down the road,  Whatever causes it...they're just like a toilet,...sometimes they begin to leak a bit and you just tighten 'em up.

It's a very simple thing to try as it only takes a minute, just remove the inside cover, and tighten up those 4,  5/16" or 3/8" mounting bolts/screws.

That's what fixed my mine after it leaked all over my inside ceiling one summer day. 

:)
 
Yes. It would be helpful to insure the mounting bolts are tight.

Based on the information given, the leak only occurs when the unit is running and leaks into the vehicle from the air return duct once the unit is shut down. It was also stated that it never leaks under a rain condition, even severe rain.

Based on that info, a main gasket leak
would be unlikely but still possible and worth checking. It would be more likely that a condensation blockage would be found.
 
I guess he could try it....

Like I said...That's what fixed my A/C leak.... ;) 

 
Thanks for the conversation on the topic!  I still haven't been able to get up top to take a look, but we had an absolutely torrential downpour here the other day, so I went over to the storage lot to see if I could get a shower in the salon.  Despite the rain coming down in buckets and even sideways for a little while, there wasn't a drop of moisture in the A/C unit.  That particular rainfall was more severe and longer-lasting than when there was last water coming through the return air grille.  I may try to hobble up there this weekend if we get a nice day because I think the condensation drain blockage is the most likely culprit.  That seal is a brand-new one that is only about a year old.  The best theory I can come up with is that it can drain well enough normally, but with the increased humidity of a heavy rain the drain just get overwhelmed.
 
Yes. The increased moisture removal by the A/C would increase the flow of the condensation track. That could explain the leak during rain events when the unit is running. It is a very fine line but it may be that the blockage is at its infancy and getting worse as times moves along.

My other thought was that possibly the rain water is damming up the condensation track causing it to back up.

Could be a combination of all above. Getting an eyeball on it should solve it.
 
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