Clean roof air conditioner evaporator coil

September 17, 2017, 03:37:20 pm

We just completed cleaning our roof air evaporator coils and the little fins now shine. Each took about 3 hours to complete. Main panel air conditioner breakers are turned off.

Unscrew the big cover and turn over on roof with towel under to protect painted surfaces. We put tools inside cover for organization and to keep cover in place.

Remove many short screws with hex heads that keep electronics and evaporator coil covered. Vacuum, clean and straighten fins. Then spray lots of foaming coil cleaner on evaporator and watch it bring out many small dirt particles. Repeat foam cleaner applications many times and then rinse with couple bottles of water, capturing drain with towels.

Doing the same foam cleaner on the exposed condenser coil is much less productive as these coils are not filled with dirt particles like the evaporator which takes in room air over a wet coils. Condenser is dusty and had a little sand from beach wind storms, so vacuum sucking and blowing does a good job.

We oiled motor with a spout oiler and generally used the vacuum to blow dirt and dust from everywhere including small electronics compartment.

Our roof air units came with electric heating elements, instead of being heat pumps. We have never used the roof air to heat the coach because there are lots of ways to heat, but only one way to cool, so why wear it out to heat. Besides heat is much better rising from floor instead of trying to push warm air from roof to the floor.

So while the inside covers were off, we decided to remove the electric heating elements that are mounted in front of the evaporator coil. Remove one short mounting screw, pull out heater stem, open electric box, unplug two wires, remove cable grommet, tape up wires and tuck out of the way. Now evaporator coil surface is unencumbered and easier to keep clean from inside.

When we put the big plastic cover screws back in, we have reduced the chance of cover breaking from stresses around the holding screws. We have a piece of rubber inside and out over the mounting hole and a fender washer under the screw head to spread the pressure.

We see plenum temperature of 40 degrees measured with permanently mounted stem-dial thermometer.

Re: Clean roof air conditioner evaporator coil

Reply #1 – September 17, 2017, 03:45:59 pm

A few pictures of our roof with air conditioner cover removed.

Re: Clean roof air conditioner evaporator coil

Reply #2 – September 17, 2017, 04:18:01 pm

Good job, Barry.

Particularly in humid areas, this needs to be done ANNUALLY! The filters on RV A/C's are really poor, so lots of dirt gets by them to be added to the water condensing on the evaporator.

When you first turn on the roof A/C, if you get that "wet dog" smell, you are well past due for an evaporator cleaning. And certainly clean the condenser while you have the cover off.

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