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dale farley
05-22-2015, 10:26 AM
This is subject that has been discussed before but one that is worth mentioning again. Some of the newer members may have never thought about it.

Although this specifically addresses roof air conditioners, it is applicable to all bus AC units. In addition to changing/cleaning your filters, you can clean the coils and clear the drain lines.
I assume everyone who has roof airs, has drain lines that drain the condensation under the bus. It is rather important that we watch the drain lines and make sure they are not clogged up. I know one Prevost owner who did not do this, and the damage cost over $8000 for repairs to the ceiling and wall of his coach.

When the drain lines stop up, the result is very similar to what happens in your house. The water has to go somewhere, and when the trough inside the unit gets full, it starts running over. In your house, it usually messes up your carpet, wood or tile. In the bus, the water may run over in your ceiling area. It can do serious damage to ceilings, walls, and floors before you know what is happening. I would recommend checking your drains and flushing with a small amount of detergent and water at least once every couple years.

The last time I did this, mine were working fine, but I still added a few drops of dish detergent and flushed the lines. I was careful not to get any of the detergent on the coils. In my case there was one drain on each side of the AC unit. The 2 lines on each unit "T" into one drain line that goes under the bus. Ray Davis said it was suggested that you blow out the lines from the bottom. That may or may not clear both sides if they are connected the same way mine was, but the theory does make sense. Cleaning of these lines is a rather simple but important maintenance item.


Switch off all power to each unit, and remove the outside cover and the sheet metal cover that encloses the electrical connections. Locate your drain line and mix some water and detergent and see if it flows out the drain. If possible, blow out each line with low pressure air. I did this with a long nozzle on my air line. While you are in the unit, gently blow the dirt and debris from the coils. High pressure may damage the coils. This procedure may prevent serious problems in the future. Always be cautious when walking around on your roof. It is best to use something to walk on and therefore, distribute your weight. Plywood or thick sports pads make a huge difference. At a minimum, put your weight on the joints when you step. Be careful that you don't fall off the bus.


Dale & Paulette

JIM KELLER
05-23-2015, 07:55 AM
And always have someone around in case you knock the ladder down that you used to get up on the Bus ! I have used a slightly different method over the years because Sandy taught me ladders are for lades. I attach a vacuum cleaner to the bottom of each drain hose for a few seconds. Job done.

Pablo Kruse
06-14-2017, 05:06 PM
Does anyone know where or if there are return air filters in my 2004 Royale. I cleaned the units on top of the bus but can't find the inside filters?

dale farley
06-15-2017, 10:42 AM
There should be filters at the return air inside the bus. I would assume they are either directly under the AC units or in the air duct under the units.

Gil_J
06-15-2017, 11:29 PM
There are a few Royal owners here. Hopefully, they see your question.

Some converters never installed filters on their roof airs. You might also call Royal Phoenix and ask them.

Prodriver
08-10-2017, 02:50 AM
My rear cruise air has quit and I am having it replaced at Mira Loma this week. They said it will be a new unit, the same as what was in there. I thought they didn't make them anymore or is there a Domestic cross-over part number?

Gil_J
08-10-2017, 07:53 AM
Dometic no longer shows them on their web page, except the marine versions with sea water cooling. I don't believe there is any shortage in parts, especially given most marine unit components are the same. I believe AAP in southern VA is the dominant retailer.

Are you having Prevost replace it?

Prodriver
08-10-2017, 12:10 PM
Yes they sent me a quote for parts and Labour. Apparently they have an AC teck that knows these units inside out. They wanted to swap the whole unit out instead of messing with parts? What are your thought Gil?