Servicing RV Roof Air Conditioners

[wolfe10]

Servicing RV Roof Air Conditioners

Air return filter(s) need to be cleaned/replaced frequently. Shine a flashlight up into the air return to determine if you have accumulated dirt on the filter(s). The filter area is small, so it is not unusual to need this serviced weekly with heavy use.

If a ducted system, check for air tight connection to duct(s).

Just snug the 4 bolts holding the roof-top unit to the inside unit. They are accessible by removing the inside cover. You want to minimally compress the foam roof gasket. Do NOT over-tighten. If water leaks in from the roof, try tightening a little��"if it still leaks, replace the roof to A/C gasket (available at any RV store).

Other service items such as condenser, evaporator, fan motor and capacitors are serviced from the roof. To service these, turn A/C 120 VAC power OFF at 120 VAC breaker box or just unplug coach from shore power. Obviously determine that you can safely climb on the roof. Remove the A/C shroud to service these items.

There are TWO sets of coils on the roof. The one you see is the CONDENSER and can be easily cleaned with water or compressed air. Do not get water into the electrical area.

The other coil, the EVAPORATOR, is inside the evaporator housing. Particularly if you get that moldy, cave-like smell when first starting the A/C you need to clean it. This is likely a once a year issue in humid climates where the evaporator stays wet much of the time. Use a professional evaporator cleaner available at any HVAC store and a tooth brush (NEVER your own).

And while you are on the roof (WITH POWER OFF), check all electrical connections and also that the electrical capacitors are not deformed or leaking. Do not touch the terminals on the capacitors, as they do retain a charge even with power off.

Some fan motors have oil ports on each end of the fan motor, some have sealed bearings. If oil ports, add 3 (not more) drops of light machine oil/sewing machine oil to each port. Also, insure that the fan motor is tight on its mounts. Lastly, check and remove mud dabber nests that can throw fans off balance or short out electrical connections.

Brett Wolfe

[tbutler]

Several years ago we began using WEB Odor Control Filters with a filter layer and an activated carbon layer. These come in a cut-to-size format complete with a plastic grid to provide backing for the filter to keep it from being drawn up into the air intake. I found these at Lowe's for about $10. You can use them in two ways. I started by cutting them the same size as the original filters. After they became dirty, I would reverse them as half of the filter is not over the air intake and doesn't pull as much air. Lately, I have begun cutting them to half the size of the original filter and using the original filter folded in half for the non-intake area. I can get three of these filters out of one package so the cost of each is about $3. The filters are much more effective than the foam filters that were original and the carbon layer is supposed to control odors. The original filters were always pulled up into the air intake and were thus not very effective. The plastic grid takes care of this problem. I can even use the scrap pieces to make an effective filter when I have collected enough of them.

These filters are green in color which makes it easy to glance up at the filter and notice the dirt on the surface of the filter. I recently replaced the filter on the front air conditioner after just three weeks of near full time air conditioner use. During the summer and/or dusty conditions, watch your filters carefully. They can collect a lot of dirt fast. One factor to consider when making a change in filters is the air flow. These filters do not seem to reduce the air flow. A reduction of air flow could cause problems with the air conditioning unit freezing up.

[klntl]

What is the best way to determine why the compressor is not operating. I know there is a mother board that could also be the issue. Any help would be great. This is a 1997 unit and we have spent all of our vacation money on repairs before our vaction begins. Thanks for any advise.

[wolfe10]

What is the best way to determine why the compressor is not operating. I know there is a mother board that could also be the issue. Any help would be great. This is a 1997 unit and we have spent all of our vacation money on repairs before our vaction begins. Thanks for any advise.

You need to tell us more about what you have.

What brand A/C? Model if you know it?

Ducted or non-ducted?

Remote thermostat or on the A/C unit?

Does the fan start OK, but the compressor doesn't kick in-- if not, please tell us exactly what works/doesn't work.

Do you have adequate voltage (108+ VAC)?

Brett

[klntl]

Its a Coleman ducted unit with a wall mounted thermostat. The fan operates but the compressor will not click on when you lower the thermostat. Appears to have good voltage to the unit from the inside. I just wonder if there is a way to test the compressor or the board with taking it to a pro.

[wolfe10]

Thanks for the additional information.

If you are safe going up on the roof, with 120 VAC power OFF, remove the A/C cover. Remove the cover plate for the "electrical" area.

Check the capacitors for leakage or swelling, or overheating. Do NOT touch the terminals, even with the power off, they can still be charged.

Look over the wiring to the compressor for loose connections.

Brett

[klntl]

Thank you I will. And thanks for helping everyone all the time. It is greatly appreciated.

[3507phaeton]

kinti,

You described the same problem I had with my Coleman unit. The compressor was out and I needed to replace the whole unit.

[harriser1@live.com]

Brett: Thank you for posting here. I have a question for you.

I have a 1998 Bounder 36s with two roof mounted AC units. They are Coleman ducted units with a wall control panel located in the salon. There are temperature sensor mechanisms in the salon and in the bedroom. The control panel has a separate control for each unit. You can choose heat, low fan, high fan, low a.c., high a.c. or auto. When you choose high or low a.c. the fan runs continuously and the compressor cycles on and off - just as expected. My question is about the auto setting. I would think that with the auto setting, the fan and compressor would come on only when the temp. rises above the setting chosen on the thermostat. Here is what mine does. If I set the temp for 72, then the fan cuts on at 74 and then the compressor cuts on. The coach cools down to 70 and then the compressor shuts off but the fan keeps running. The fan does not stop running. The temp goes back up to 74 then the compressor cuts on and drops the temp back down to 70. Again, the fan never stops. I had a 2004 travel trailer with a Dometic ducted ac with wall control. On that unit the fan and compressor only ran when necessary and once the desired temp was reached, the thing shut off and the fan did not keep running. Is this an older design characteristic on my 98 Bounder? Is something wrong or are the units performing as they should?

Thank you.

[wolfe10]

Harriser,

Welcome to the FMCA Forum.

I do not know the specifics of your particular model.

Here is the factory contact information for Coleman RV A/C: http://www.rvcomfort.com/rvp/contact.php

Might cut and paste your post and send it to them for their response.

Brett