RV Doctor – Roof Air Conditioner Leakage & Drainage Issue

Dear Gary,
I have an air conditioner on the roof. I had a problem with water leaking inside through the air conditioner when it rained so I sealed around the edges of the roof unit. I have since been told not to do that, that the condenser must drain onto the roof and now I will have that condensate coming inside. I removed the shroud but am unable to locate the hole or holes in the drain pan to see where it drains. Could you tell me where the holes are located so I can make sure they are clear and draining properly? The unit is so old that I am afraid to remove it to replace the 14-inch gasket. – Gus Tarver, (Merritt Island, FL)

Answer:

Gus, indeed the only water seal on the roof air conditioner occurs at the perimeter of the 14-inch opening. The air conditioner sits atop the 14-inch gasket only. Condensation must drain through the pan and onto the roof of the RV outside of the 14-inch opening. The holes in the pan may be located under various internal components making them hard to see by simply taking off the shroud. You may be able to locate them by using a flashlight and a mirror, but they must be clear to allow the pan to drain.

The fact that you have rainwater leaking under the air conditioner mandates the unit be removed from the roof and a new gasket installed. It’s likely the constant weight and possible over tightening of the mounting bolts have compressed the gasket beyond usefulness.

Remove the interior shroud and the filters and you should be able to see the mounting bolts that can be removed. These bolts sandwich the roof between the bottom of the air conditioner and the interior plenum. Be sure to disconnect the AC power before removing the plenum.

Once the plenum is down inside the coach, the air conditioner can be carefully lifted off the 14-inch opening on the roof. Take care lifting the unit so that the roof material does not tear during the process. It’s best to use two people to remove the unit from the roof.

Once exposed, the 14-inch opening can be cleaned and a new gasket installed. Carefully inspect the roof for problem areas around the opening. Do not over-tighten the mounting bolts when reinstalling the A/C unit. You only want to compress the gasket enough to prevent leaks while securing the air conditioner.

(Please feel free to comment, however, please also note that due to the volume of communications I receive from multiple channels I cannot guarantee a personal response in every instance. However, questions of an overall general interest may be considered and published in an upcoming RV Doctor column.)