Cleaning OTR A/C evaporator

[Joe Cannarozzi]

I'm looking to solve what I believe is poor air flow at the registers at the bottom of the windows for the otr a/c.

When we bought the bus there were no air filters at the evaporator and can only guess how long that it was run without them. Based on the large amount of dirt that has accumulated in a relitivley short period of time on the filters we installed, I think that there is probably some dirt and obstruction in there.

You can see the leading face that accepts the filters but the other side is not visible, its sandwiched up against the heater core. Also the fins are a very tight pattern.

Does anyone know of a safe product or a home remedy we could use to try to clean it out? I do not want to just spray water in there for fear of making any obstruction harder to get out later.

I'm thinking an emulsifier.

I have used a emulsifying bio-degradable engine cleaner that rinses off with a hose and it worked GREAT. I have read the lable and it does not say anything about using it around aluminum and with the large percentage of aluminum parts on todays engines I think it would be O/K but I would like some suggestions.

Also I have noticed that the filters we have provided, 2, pleated paper, 20 by 20, for a home furnace style, side by side were a little damp when I pulled them. What was originally in there, a metal reusable one similar to what slides in above the evap. for the drivers a/c? The face of the evap is 20 by 40 and with that next bay back being the plumbing bay in a motorhome we cannot use a one piece filter that probably exzisted originally due to the fact that you can not get it in and out.

[Jon Wehrenberg]

Joe,

There is a Simple Green designed for aviation and it is labeled Aviation Simple Green. You should be able to buy it on line or at any local general aviation airport operation. It will not harm aluminum and I would suggest that.

Other cleaners may work fine, but unless you can be certain you have rinsed them off you may end up with future problems. The aviation version of Simple Green is specifically designed to be safe on aluminum.

[Joe Cannarozzi]

Thanks Jon

How about the filter on that evaporator? Is it a reusable washable metal, or disposable pleated paper?

[Jerry Winchester]

Maybe you just have the coach equivelent of a rat in the skimmer? I think the PlasticKrakster knows how to handle that kind of deal.

[Jon Wehrenberg]

Joe,

I have a three element filter in the return air to the evaporator. It is not a fine mesh but a fairly open weave that I can wash with a hose. I don't think you need a filter that traps microbes, but you do want to catch dust and maybe dog hair.

I clean mine once a year and it is not real dirty so if you can put a filter in the return duct a normal furnace filter or equivalent should do the job. A pleated paper is likely to choke off the air flow.

[Joe Cannarozzi]

This filter, it's not right up against the evaporator but in the register in the floor for the air return?

In addition, I have learned that there is a product you can get at the appliance repair shop called Coil Bright that is specificly for this purpose. There is one for the evap. and one for condensers, the ladder being stronger.

I'll be trying for it Mon.

[Joe Cannarozzi]

Thank you Jim, not to worry I can remove it.

My question was directed to Jon and where Liberty has placed it on his bus.

[win42]

Joe: Jons right on filter density. If you put a more restrictive filter you will choke the air supply. Check your fan blades for dirt build up. Forward curved fan blades lose their eficiency when the curved blades fill up with dirt. You may also have a weak fan motor or switch causing air flow problems. Adding better filters will require larger area, you probably don't have room to provide that. Let us know the outcome, most of us have similar problems.

[Jon Wehrenberg]

Joe,

My 87 had a filter located in the hole in the floor beneath the dinette seat. I can't tell if that was a Liberty or Prevost filter.

The current coach has a Prevost filter located at the top of the evaporator bay and it consists of a rack and three filter sections located side by side on that rack. The opening from the house is located beneath cabinetry in the kitchen area.

Harry makes an excellent point about the squirrel cage fan blades. The curved portions fill with dust and the curve becomes straight impacting the efficiency significantly. He's pretty sharp for an old guy isn't he?

[Joe Cannarozzi]

Thanks

It seems to me like prevo may have changed the configuration of the evap. filter and moved it from the face of the evap. to the top of the compartment, and I'm guessen to prevent moisture from accumulating on it.

I'll be moving ours to the return air register to eliminate that issue and also make it easier to change.

[jello_jeep]

Dang Harry!,

that was actually meaningful, relevant dialog!

I am very impressed!!!

Are you Harry Hoppe? Or another ? :eek: :D :o

[win42]

Jeep: Thanks for letting us hear from the other half of your brain.

[colton]

Joe, go to an air conditioning supply house and get a no-rinse evaporator cleaner and apply it with a pump up sprayer. As the name says you dont have to rinse it

[jello_jeep]

Welcome Colton, congrats on post #1~~

Hope to see you around here putting up with the assorted fruits & nuts here ..

Is your /nickname at all tied to Colton Ca ?? :confused:

[win42]

Joe: In the olden days you got some carbon tet and rinsed the coils. Now you can't buy carbontetrachloride. They packaged it as coil cleaner and charge four time the price. All those nifty brass fire extenguishers used to be full of the stuff.

[Joe Cannarozzi]

Here is what we came up with. Picked it up at the appliance repair. Says it can be used strait if need be but suggests diluting anyware from 3 ta 1, to, 6 ta 1. No rinsing nessesary, but I'm gonna anyway. 20 bucks a gal. aprox. The counter girl said this is the most popular of 3 different types they carried.

1459

Thank you everyone for your inputs. Let you know how it does.

[Joe Cannarozzi]

Good results. First a significant improvement when pulling the furnace style filters on the face of the evap. and switching to a filter cloth at the floor register.

Another smaller improvment, but still noticable, after flushing the evap. with cleaner. I was able to spray the face of the evap. reasonably easy cause the gen. is out of the bay forward of it and I was being a bit of a contortionist spraying from the plumbing bay that is to its rear, combined with I'm pretty slim. All I can say about this job is good luck folks, gettin at it aint easy. Unless your system was run without a filter like ours was it may not even be necessary.

Although we have measurable improvement, I'm still disapointed at the uneven flow to the windows. For example, the forward most windows furthest away from the blower, crank, while others that are closter are weak? Then there is one that has good flow on one end of the window but poor on the other. Wierd and frushtrating.

All in all a big improvement.

[Jon Wehrenberg]

Now you can appreciate why most converters dream up reasons why OTR is not as good as their home made system.