Troubleshooting my Coleman air conditioners

[HandyDan]

After removing my Coleman air conditioner from the rear of my Holiday Rambler, I decided to see why it no longer worked.  It ran just fine last summer but over the Labor Day weekend the fan started to run slower and slower until finally it just quit.  It, also, was not cooling well even when it was running okay.

Well, I decided to oil the motor and see if that would get it turning.  I sprayed some LPS1 greaseless oil on the bearings and down the oil chutes.  I turned the fan by hand until it started to loosen up.  After soaking for a few minutes, it was turning like new.  Keep in mind I am only turning it by hand, I haven't applied power to it.  I then added a little 20wt oil down the chutes as the owner's manual suggests.

Having the motor lubed, I then turned my attention to the sheet metal covers to the condenser (or is it the evaporator?  I can never remember which is which).  I took the 20 screws out of the front cover and lifted it off.  I was astonished to find that the radiator was covered in mud dauber nests!  It was no wonder it wasn't cooling, there wasn't enough surface to cool.  If one didn't pull the sheet metal, one would never know there was a problem.  I pulled out as much of the clods as I could and decided to look at the other end.  I took the shroud off the fan and looked behind the radiator on that end.  It, too, was covered in mud dauber nests.  I got the power washer out and made short work of cleaning the mud out of the fins.  Even the wiring was covered in mud dauber clods.  I made a big mess but I got it cleaned out.  I dried up what I could and started putting everything back together.  I'm sure if I put power to it, it will work better than ever.  However, even if it does, I'm not putting it back on the Holiday Rambler.  I think I will put it on my old Class C Tioga Arrow that I might make road worthy again, someday.  I blew the compressor in that one during a brown out at the campground. 

I then decided to look at the other Coleman that was now resting comfortably on the rear of my MH.  I took it apart while on top of the motorhome.  At first I was afraid to walk on the roof since I'm not a lightweight, but after looking at how the Holiday Rambler is put together, it put my mind at ease.  It has a substantial welded aluminum framework topped with 1" of Styrofoam with 3/4" of plywood and more Styrofoam before the aluminum sheet roof.  I think I am safe.  The second Coleman was just about a repeat of the first one.  Not quite as bad, but still needing attention.  I cleaned it up, oiled the motor, and put it back together.  I plan on getting a new outer shroud for it since the original one is starting to break up.  It works better now and I hope the mud daubers find another place to live. 

[ClydesdaleKevin]

We've had a similar problem with all of our air conditioners, but it wasn't caused by mud daubers...it was caused by our cat, dogs, smoking, and fulltime RVing in general.  The inside filters aren't all that efficient, and over time...a short time with pets and fulltiming and all...the INSIDE of the radiator fins get clogged up with mixture of dust, dog and cat hair, smoke, etc.  Then the drain pan outlets get clogged and you get drips inside the RV...oi vey!

The solution is to remove the ceiling unit periodically and clean it all out.  Took me a while to figure it out, but now its just a part of our regular periodic maintenance. 

Kev

[DaveVA78Chieftain]

I also recommend you look at the capacitors.  The cans should crisp and physically look like they were just made.   Not bulging out (swelling).   They can do that with age.    Easy to replace.

Dave

[moonlitcoyote]

Can anyone explain this a little better about cleaning certain parts, maybe even add a pic or 2, my ac runs fine but it doesnt seem to cool very well. It's 90degrees in here with it running and when hubby gets home he's gonna stick a fork in me, cause I am DONE!

[Oz]

In addition to the feedback you'll get, look at your make and model, go to the member area and dowload a service manual.  I don't know what you have or the age of it but, you might find those manuals helpful. 

[ClydesdaleKevin]

Basically you have to make sure your fins...inside and out...are clean.  There is no mistaking what they look like...they look like a radiator.

Inside the cooling unit, which you can see once you pull the plastic ceiling covers off, are the inside fins, which periodically get clogged up on us with dog hair, etc.  Clean them out with a vacuum and a brush attachment.

Outside, you have to pull the plastic cover.  Depending on the model of your AC, you'll either see one or both of the sets of fins, or you'll have to remove sheet metal covers over them.  Generally there is one in the back and one in the front.  You can use the vacuum, or as Dan did blast them with a hose.

If you get drips inside, that is usually caused by the drains being plugged up...but can also be caused by high humidity, where the cooling unit literally ices up, and then starts to drip into your RV interior.

Kev

[moonlitcoyote]

Thanks, I'll check it out. I just had the inside cover off a couple days ago to paint it and I didnt see any fins, I'll check it again. I also had to replace the outside cover because it was broken to pieces when I bought it but didnt see any fins there either. Either I'm not very observant or the fins are hidden from view.

[cosmic]

are you hearing the compressor turn on? the older ones realy draw the power and can here it bog on the start up.
if its not kicking in go up on the roof and take the plastic shroud off and open the steel boxes that power the compressor check that the connection didn't break in that box. I fix 2 this way already when the compressor stopped working.
good luck.

[DaveVA78Chieftain]

Here is story about cleaning a RV rooftop AC that should let you know the basics.

http://www.sunlineclub.com/forums/f71/cleaning-the-ac-coils-lots-of-pics-10405.html

Dave

PS: The meter portion is a good example of how to use the current feature of a clamp on meter to evaluate circuit condition.

[moonlitcoyote]

cosmic, the compressor is working, it does blow cool air, just not very cold.

Thanks for the link Dave, that helped a lot.

[Lefty]

I've got to climb up on ours and see if I can figure out what's wrong with it too.
It will come on, and cool great...then after it reaches temp the compressor cuts off, the fan runs until it is time for the compressor to kick in again. Then it blows the breaker.
The fan function works fine, and doesn't blow the breaker.
The heat function also works fine and also doesn't blow the breaker.
The A/C unit will always start right back up after the breaker is reset, and then blows the breaker when the compressor kicks in the second time.

I'm leaning towards either a bad capacitor, or a compressor starting to fail and drawing too much power. Gotta get my multi meter out & see what's going on with it.

[DaveVA78Chieftain]

Lefty,
My bet is either the run or start capacitor.  Just replace both and the fan capacitor (they are cheap).  Finally had to replace mine after 20 years of service because they were expanding out of their cases.  Also the connections up there get corroded.

Dave

[moonlitcoyote]

In addition to the feedback you'll get, look at your make and model, go to the member area and dowload a service manual.  I don't know what you have or the age of it but, you might find those manuals helpful. 

Join the club, I dont know which make/model or year I have either.

Well I took the inside cover off and as I suspected, there is nothing inside to clean, I looked inside of it, but there really is nothing in there, I cant imagine how this thing works. Anyway, it's raining today so maybe tomorrow I can get on the roof and check out the outside of it.

[DaveVA78Chieftain]

moonlitcoyote,
Parts book for your rig (http://www.winnebagoind.com/service/wincd/1985/85wcn27ru.pdf) says the Winnebago P/N for your AC is 073742-01-000.  Referring to the 84-88 Common Parts book (http://www.winnebagoind.com/service/wincd/1985/1984-1988common.pdf ; PDF page 2), you have a Coleman 6759703 or 6759707 model AC.  There is a parts picture there that should give you a rough idea where everything is in your AC unit.  Knowing all that information we can track down most anything that might still be available for your AC unit.

Parts: http://www.sahararv.com/pdfs/552-566_Parts_Coleman-Mach.pdf or http://www.rvdealership.com/rvdstore/index.aspx?CustomerNumber=348311&Referer=http%3A%2F%2Fbryantrv%2Ecom%2Fshop%2Ehtml

Service Manual is available in our Manuals & Diagrams seciton of the Member Area

Dave

[moonlitcoyote]

Thank you Dave, out of all that, I did figure out that I have the Mach III.

Is it worth trying to buy the original filters for it, or could I use something else?

[DaveVA78Chieftain]

Either way is ok.  It is nothing more than a foam filter.  RVDealership.com (link above) shows one for the 6759707 for $3.50.

Dave

[Froggy1936]

HI M I just buy the largest humidifier filter @ Walmart then cut a piece to cover the intake area (the inside grillwork) you can tie it in with wire ties from bread pkg etc  Then vacume it clean or replace it they get coated pretty quickly Frank

[ClydesdaleKevin]

Forgot to mention you also need to remove the 3-4 hold down bolts that hold the metal part of the inside shroud in place, pull the power plug, unscrew the accordion like part where the air blows into the coach...and THEN you'll be able to see and clean the inside fins.  Been a while since I worked on an older Mach.

Kev

[moonlitcoyote]

Thanks all, I will get on the roof the next nice day I feel adventurous and clean it all out. I also didn't know they were foam filters, mine are "sos pad" type, must be something a PO put in it. Anyway, maybe I can find some at walmart since it's difficult to order things online when we dont stay in 1 place for very long. I appreciate all the help.. MJ