Cleaning the cooling coil on Dometic AC/heatpump units

September 14, 2013, 05:02:23 pm

I decided to clean the cooling coils on our AC units because my wife, Pat, started to notice a distinct odor when the units started. I'm usually oblivious to such issues. I had thought about doing this in the past, but always put it off because it involved removing the AC shroud and sheet metal cover in order to get to the cooling coil. Room air is pulled up and through this coil for cooling (or heating) and since the surface mounted filter is minimal, there is a lot of potential for dirt to be trapped in the fine structures of the coil. This proved to be the case.

Below are some pics of what I did. This is not a big deal project, but I thought some might find it useful, especially those that have been putting this job off! It probably needs to be done every couple of years.

1. The first step is to remove the plastic shroud by removing the four corner screws. These a subject to a lot of sun and crack easily with age. But they are available from Dometic. Just make sure you get the model with the vent holes on the side....these are for the heat pump.

2. Once the plastic shroud is removed, the next step is to remove the sheet metal cover. There are 9 sheet metal screws plus the two that hold the cover to the wiring compartment on the side. When I lifted the cover off, I found a thin layer of foil-backed fiberglass which had been attached to the inside of the sheet metal (foil facing inward). This stuff was in pretty bad shape, so I removed it and replaced it with self adhering foil backed insulation (R3) that I found at Home Depot (about $18).

3. I could not find any replacement weather stripping, so I carefully removed it from the sheet metal cover and used 3M outdoor double stick tape to reapply it.

4. With the sheet metal cover off, the cooling coils were easy to access. As can be seen from the pic below, it really needed to be cleaned. I used a foam cleaner that I also got from Home Depot (recommended on this forum). The cleaner claims that it does not need to be rinsed, but I used a gentle stream of water (a hot water tank cleaning tool worked well to direct the stream of water) to remove the dirt. I also used it to flush the condensate outlets. There was a lot of dirt that came out.

5. Even though I tried to keep the water away from parts other than the cooling coil, I found this to be a messy job and I had to frequently clean up water on both sides of the coil. I also put a towel in the opening to the coach to catch any stray water. After I was done cleaning the coil I made sure all the electrical connections were dry.

6. Finally I reassembled everything and thankfully the AC unit restarted!

Re: Cleaning the cooling coil on Dometic AC/heatpump units

Reply #1 – September 14, 2013, 05:08:07 pm

Excellent job and description.

Anytime you get that "wet dog" smell when you turn on the roof A/C, it is time to clean the evaporator (and do the condenser while you are up there).

Brett

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