How To Install A Coleman RV AC Rooftop Air Conditioner

Source

An overview of the Coleman rooftop AC

Coleman RV air conditioning units are perhaps the most well known of RV ACs in the world of RV users, whether they be motor homes, camper travel trailers, or pop-up campers. Along with other fine camping products, the Coleman rooftop AC units are considered one of the most efficient and reliable brands made.

Installing or replacing a new AC unit is something even the most hands-off type of person can accomplish with a little study and work. This article is intended to walk you through the steps of installing a new Coleman AC in a camping unit, or replacing an old unit, no matter the make or model.

Starting the replacement process

Remove the ceiling assembly first
Remove the ceiling assembly first
The RV AC tension bracket with retaining bolts and wiring exposed
The RV AC tension bracket with retaining bolts and wiring exposed
Remove the retaining bolts
Remove the retaining bolts

How to Determine the Correct Coleman AC unit

If your new AC is a replacement model, it will be necessary to determine which model to use in your travel trailer or motorhome. Coleman rooftop AC’s are available in two models. The 13,500 BTU (British Thermal Units) model is perhaps the most purchased of the two models offered.

It is often used in applications where two units are used to cool a large motorhome or camper trailer. Working independently from each other, these 13,500 BTU units can be used singly or together for efficient cooling, depending on how hot the weather is.

For those middle sized camper trailers or motorhomes there is the Coleman Mach 15 air conditioner. This fine unit fits the niche perfectly with enough cooling power to keep you cool on the hottest summer days. Installing one of the Mach 15 AC units is no more difficult than the 13,500 BTU model.

Check your old rooftop unit to determine the correct size if you have any doubts as to which Coleman unit to purchase. Both of these air conditioners may be found at very reasonable prices on this page.

Buy the best model for your particular camping unit. If ordered from this page, the AC unit you chose should arrive at your location in just a few days. In the meantime you can remove the old RV AC unit and prepare for the new one.

Repair or replace your RV AC unit?

Old AC fan motor with worn sleeves
Old AC fan motor with worn sleeves
Another view of fan motor and compressor.
Another view of fan motor and compressor.

Removing the old rooftop air conditioner

The first step in removing the old unit is to detach the ceiling assembly from the unit by removing the screws holding it to the ceiling. There are normally only four screws which need to be removed, but some older AC units may have more or less. Hold the AC ceiling assembly up with one hand while removing the screws to prevent the assembly from falling abruptly.

It may be necessary to unplug the wires leading from the AC ceiling assembly to the rooftop unit before it is completely free. It is helpful to have someone assist you in this step for ease of removal, but the assembly can be allowed to hang from the wiring while they are disconnected. Remove the cover from the electrical junction box and disconnect the electrical line wires.

Note the wire colors and the ground connection in the old junction box as the new Coleman RV AC will use the same configuration when it is time to reconnect the electrical line to the new unit. After this step is complete, remove the long bolts from the ceiling bracket. These bolts go up through the roof and into the rooftop AC unit itself.

Detach the vent which connects the ceiling assembly to the rooftop unit. Some vents are made of thin aluminum and some use a flexible vinyl tube to make the connection. Both use screws to hold them in place. At this point you will need to gain access to the roof of the motorhome or camper trailer.

Ladders and padding help to prevent damage to the RV roof and exterior.
Ladders and padding help to prevent damage to the RV roof and exterior.
Removing the old AC shroud
Removing the old AC shroud
Use a thin putty knife to help loosen the gasket
Use a thin putty knife to help loosen the gasket
Clean the area around the duct where the new gasket fits
Clean the area around the duct where the new gasket fits

Coleman Rooftop RV Air Conditioners

Coleman 13,500 BTU Roof Mount Air Conditioner
Coleman 13,500 BTU Roof Mount Air Conditioner

The RV AC used in this article. Everything needed is included in the price.

 
Coleman 15,000 BTU Roof Mount Air Conditioner
Coleman 15,000 BTU Roof Mount Air Conditioner

15,000 BTU. For a little more cooling power!

 

Why buy a new RV AC?

The photos used to illustrate the steps necessary to install your new Coleman AC unit are of a 1986 Airstream Sovereign travel trailer. The old Coleman Mach had seen its better days and had given many years of dependable service. It still cooled fine but the fan motor sleeves had worn to the point of needing a nudge to get it going.

Since this AC fan motor had sleeves instead of standard bearings, the shaft itself was worn prohibiting a rebuild because of the expense. Instead of only having the bearings replaced, it would be necessary to replace the shaft along with the winding mounted on the shaft. A new motor would perhaps be cheaper to install.

Besides the fan motor problem, the RV AC shroud had begun to develop cracks at the stress points around the four retaining bolts and in some of the air vent louvers. Replacing the old shroud isn’t cheap either. So, all things considered, purchasing a new Coleman 13,500 BTU air conditioner was the best option.

If the AC compressor in the old Coleman AC went on the blink, which was entirely possible, the owner could have more than paid for the new Coleman unit by the time a new AC compressor was purchased and installed. The combined cost of the new AC fan motor, shroud, and compressor was just not acceptable when a new unit would solve the problem and perform more efficiently.

Removing the old rooftop air conditioner

Care should be taken when removing the old rooftop AC unit to prevent any damage to the motorhome or camper trailer roof.

For installation of the new Coleman AC unit into the Airstream travel trailer, we used thick padding to protect the surface where the ladder was used and on the roof itself.

Motorhome roofs are normally rubberized so the chance of damaging them are less than on a metal roofed RV.With the electrical wiring, the retaining bolts, and the ducting unfastened, the old unit is ready to remove.

It may be necessary to carefully slide a thin putty knife between the bottom of the old AC unit and the roof surface as any previously applied roof sealants will have caused the old AC unit to be adhered to the roof.

When the old AC unit is removed, carefully lower it to the ground. Clean the area around the vent hole carefully being sure no rough spots or adhesives remain to interfere with the new seal.

Remove the shroud from the new Coleman AC before transporting it to the roof of your camper. Check for any shipping blocks or other objects which may interfere with the moving parts of your new AC.


Installing the new Coleman rooftop air conditioner

The new air conditioner with shroud removed
The new air conditioner with shroud removed
The new AC on the roof of the Airstream
The new AC on the roof of the Airstream
Attaching duct and new ceiling flange
Attaching duct and new ceiling flange
Wiring the ceiling assembly
Wiring the ceiling assembly
The ceiling assembly after installation
The ceiling assembly after installation
Installing the new AC shroud finishes the job.
Installing the new AC shroud finishes the job.

Finishing the AC installation

Once you have centered the new unit over the duct hole you may attach the retaining bolts and bracket. Tighten the bolts gradually moving from one to the others until the seal is uniformly tight against the roof.

Do not over tighten these bolts. They just need to be snug enough to keep water from seeping beneath the gasket and you can always tighten them further to stop any leaks if needed.

Replace the shroud using the retaining nuts and being sure the shroud is securely fastened to the unit. You are finished with the rooftop part of installing the new AC unit.

Follow the instructions provided with the new Coleman unit to attach the flexible duct in place.

If you purchased the optional heating element now is the time to attach it to the ceiling assembly. Reattach the electrical line wiring to the wiring in the unit junction box.

Using the provided screws, attach the ceiling assembly in place and re connect the power source to the motorhome or camper trailer.

Test run the new AC unit to check for any malfunctioning parts or a lack of cooling or heating if the heating option comes into play.

Your new Coleman rooftop RV air conditioner will give you many years of trouble free service if maintained properly.

More by this Author


Comments 78 comments

Hello, hello, profile image

Hello, hello, 6 years ago from London, UK

That sounds great and you way of writing made it so easy to understand. Great hub.


Randy Godwin profile image

Randy Godwin 6 years ago from Southern Georgia Author

Thanks again, Hello, hello!


Chris Tatman profile image

Chris Tatman 6 years ago from Mattoon, IL

wow very in depth, thanks for all the information.


Randy Godwin profile image

Randy Godwin 6 years ago from Southern Georgia Author

Thanks for reading, Chris! And welcome to Hubpages!

Randy :)


habee profile image

habee 6 years ago from Georgia

Voted up and useful! Is that Joe's butt in the pic??


katiem2 profile image

katiem2 6 years ago from I'm outta here

Great topic, I enjoyed reading your hub on coleman air conditioners. Bravo! Thanks and Peace :)


Randy Godwin profile image

Randy Godwin 6 years ago from Southern Georgia Author

Wow Katiem2! You must be really bored! LOL! Thanks for reading and the comments.

Randy ;)


Springboard profile image

Springboard 6 years ago from Wisconsin

Might be something I'll definitely have to look into. My wife and I are buying her cousin's pop-up soon, and it doesn't have AC. I'd like to have it eventually, but I'm sure installation from scratch will be kind of costly, and may not ultimately be worth it. I'm thinking, don't they have plug in AC units now which don't have to be hung outside?


Randy Godwin profile image

Randy Godwin 6 years ago from Southern Georgia Author

The installation of a rooftop RV AC unit will cost you very little other than the unit itself, Springboard! Most pop-up camper trailers already have a 14"X14" roof vent which is standard size for a rooftop RV AC unit.

Yes, there are portable AC units which only require a vent of some sort. A window may be used or they may be vented through the floor or wall.

Thanks for reading and commenting!


troy 6 years ago

the coleman 15k does have a compressor issue. If you ever experience the compressor trying to kick on and does not, be assured the compressor has locked up. I am currently looking for a compressor only to fix one that is 4 months old. Leaked around the welds. Good luck and happy RVing


Randy Godwin profile image

Randy Godwin 6 years ago from Southern Georgia Author

Thanks for the info, Troy! The compressor should be under warranty if the unit is only 4 months old! I would contact the Coleman company and ask for a new unit1


Mark in Belmont,Ont/Canada 5 years ago

Great Article ...!!! Thanks for sharing!


Randy Godwin profile image

Randy Godwin 5 years ago from Southern Georgia Author

I appreciate the appreciation, Mark! LOL! I'm glad the info is useful to RV owners. :)

Randy


jim 4 years ago

why is my air conditioning unit make load humming sound inside camper


Randy Godwin profile image

Randy Godwin 4 years ago from Southern Georgia Author

Hi Jim. there are several reasons why an A/C unit might make loud humming noises while in operation. If the compressor is older it may be getting ready to go out or the rubber shock absorber bushings used to hold it down could be worn or loose.

The fan motor could also be in need of replacing, or there could be a mud dauber or other obstruction which is making the fans--either the squirrel cage or regular bladed fan--be out of balance causing vibrations.

It will likely be necessary to remove the shroud while the unit is operating to actually find out the reason for the noise. Sorry I cannot be more specific as there are so many causes for such vibrations. Feel free to ask for more info if needed.

Randy


Ron 4 years ago

How do you remove the round air vent covers in the ceiling on a motorhome?


Randy Godwin profile image

Randy Godwin 4 years ago from Southern Georgia Author

Sorry Ron, I'm not familiar with these "round" vent covers in a motorhome. However, they should be accessable with clips or screws. Perhaps someone else will drop in with a clue here.

Randy


Ron 4 years ago

Thanks Randy. Are you by chance related to Mike and Greg Godwin from Hahira/Valdosta?

Ron


Randy Godwin profile image

Randy Godwin 4 years ago from Southern Georgia Author

I do have relatives in Valdosta, Ron. One named Michael for sure. My first cousin, Bobby, used to be the band director at either Lowndes or Valdosta High School. I forget which. But then, there are some Godwins around which I know but are not related to. I assume you live in this area? I attended Cook High School. Small world, eh?

Randy


Ron 4 years ago

My wife's father is Willard Godwin, and he lives in Jasper. His brother and his family live in Hahira/Valdosta. Just wondering if you were a relative...


Randy Godwin profile image

Randy Godwin 4 years ago from Southern Georgia Author

Ha, my middle name is Willard, but apparently we are no relation. Who knows though, our ancestors came down here from North Carolina around the turn of the 20th century so we may have some ancestors in common. The surname isn't all that common at any rate. Thanks for stopping by and let me know if I can help you with anymore RV problems. Sorry I was little help with your question. :)

Randy


george cooper 4 years ago

hi,Randy, could you tell me what is the difference between a Coleman mach 15,and a Coleman roughneck,i need to replace the roughneck on my Peterbilt, and the mach 15 is a lot cheaper,i would appreciate any help, thanks,

George.


Randy Godwin profile image

Randy Godwin 4 years ago from Southern Georgia Author

Hey George! The Coleman "Roughneck" is simply a rooftop unit made for off road travel especially and for other uses over rough terrain.

Actually, the mach 15 has 1500 more BTUs than the Roughneck and should work fine unless you expect to be traveling over very bumpy roads or other uneven surfaces.

I hope this helps! Thanks for the question and for reading!

Randy :)


George Cooper 4 years ago

thanks for the info Randy,it will help me a lot,thanks for what you do.

George.


Randy Godwin profile image

Randy Godwin 4 years ago from Southern Georgia Author

Glad to help, George! I'm always pleased to help folks save a bit of money and time. Good luck with your new unit, whichever you decide to choose! :)

Randy


cgbrewer 4 years ago

This may seem like a silly question, but does it hurt a roof top air conditioner to run it while on an unlevel driveway. Just asking because summer is here and it would be more comfortable to perform inside repairs with the a/c running and keeping the interior cool. I know traditionally everyone had.said to keep it level, but I thought that was primarily for the propane fridge. I also see a lot of fifth wheellers with one or more roof top a/c units installed at an angle due to the angle of the roof itself.


Randy Godwin profile image

Randy Godwin 4 years ago from Southern Georgia Author

Hey CG. Today's rooftop RV AC units are designed to operate efficiently even if the RV is unlevel. Unlike older models which utilized a drain to keep the excess moisture clear from the unit, these modern AC's throw the moisture out into the air in a mist form.

Unless the unit is operating at a very extreme angle you should have no problems using it at all. Thanks for the question.

Randy


cgbrewer 4 years ago

My only problem is that my RV is relatively old (1977). And I am not sure.if it is the original ac unit. I do know it is one of the drip drain type because when it is run the condensation drips off the the passenger side of the RV by the entry door. Does that make a difference on the main question?


Randy Godwin profile image

Randy Godwin 4 years ago from Southern Georgia Author

If possible, try to put the drain side of the camper on the lower angle of the driveway or where the drain is at the back, depending on if the driveway leans to the side or downhill. This will allow the water to drain from the unit easier.

Randy


Paul 4 years ago

I am replacing my current ac on my popup with a new unit. The old unit had a strip of sticky putty underneath the gasket. Most everywhere I read there is no mention of using this when installing - just wondering if I need that for the new install?


Randy Godwin profile image

Randy Godwin 4 years ago from Southern Georgia Author

Hi Paul! No, if the roof of your pop-up is sound there should be no need to use any kind of sealant on the new gasket. The gasket is very thick foam type rubber which compresses when you tighten the brackets down. This makes a very water tight seal in most cases. Just be sure to clean the area where the gasket meets the roof material to ensure a proper seal. Good luck with the installation and thanks for the question.

Randy


Paul 4 years ago

Do you know why the original AC would have had that putty put down? We bought it NEW from a reputable Pop Up dealer, and they installed it that way - just curious why they would have done it that way - extra care just to be sure? Or maybe they had seen problems with the particular models? The old AC unit has the normal thick foam gasket, but had the sticky putty around the entire hole edge.


Randy Godwin profile image

Randy Godwin 4 years ago from Southern Georgia Author

Perhaps the roof material had something to do with it, Paul. If it has a texture to it a sealant might have been used as a precautionary measure. Sorry I can't be of more assistance as I'm not experienced in installing rooftop A/C's in pop-up campers. I would assume they mount in much the same manner as in trailers and motorhomes though.

Randy


Paul 4 years ago

No big deal - just curious. I ended up using the putty on the reinstall thinking the same thing. The OLD AC didn't leak ever, so I figured I wouldn't go against a good thing! Thanks for responding, appreciate the help. New unit is all installed, and works great.

Paul


Randy Godwin profile image

Randy Godwin 4 years ago from Southern Georgia Author

Thanks Paul! Glad to hear the new unit works fine. :)

Randy


mike 3 years ago

My roof top AC unit is leaking , i there a sealant that i could use on the exterior ,without having to remove the unit


Randy Godwin profile image

Randy Godwin 3 years ago from Southern Georgia Author

Hi Mike,

Is your AC leaking down through the ceiling assembly where the filter is located, or around where the gasket seals the unit to the roof? If it's leaking through the ceiling assembly your coils are probably clogged with dirt and a good cleaning will solve your problem. If it's leaking around the gasket a good grade of silicone sealant should do the job.


mike 3 years ago

Thanks for answering Randy . I also noticed that there is water coming in through the roof mounted light .which i don't think is connected to the AC unit .Do you have any idea how to stop that water . when we are camping and it rains we do not have a water problem . It happens during the winter wheni the camper is closed up . the water has stained the canvas on the inside .


Randy Godwin profile image

Randy Godwin 3 years ago from Southern Georgia Author

This suggests a very slow leak in the roof material, Mike. I would advise inspecting the roof in the area of the leak and using a roof sealant which will penetrate the cracks causing the problem. Check out this article to find different types of roof sealants and patches:

http://hubpages.com/travel/RV-and-Camper-Trailer-R...

Thanks for reading and for the questions, Mike. Good luck on your repairs and please ask if you need any other RV repair advice. I have many other RV repair articles on my profile page.


Marshall 2 years ago

I bought an old RV (1976) that has a lot of water damage to it and I'm going to remove the old A/C unit and seal the hole. Actually I am totally gutting the Rv and will rebuild it replacing all rotten wood. Anyway, what is the best way to seal up the hole where the A/C unit used to be? Thanks for your help.


Randy Godwin profile image

Randy Godwin 2 years ago from Southern Georgia Author

Hello Marshall, you can use a standard 14x14 inch roof vent to close the opening as all of them are the same size as the AC opening. The vents usually come with a seal kit to prevent leakage. Hope this info helps.

--RG


Marshall 2 years ago

Thank you Randy.


tj 2 years ago

I get water leaking inside when the rooftop AC is running. Is this condensation and how can I fix it?


Randy Godwin profile image

Randy Godwin 2 years ago from Southern Georgia Author

Hi TJ, yes this is condensation probably because the coils are very dirty and doesn't allow the moisture to be released into the air. You can clean them by removing the shroud and using a good coil cleaner--or even a household cleaner such as 409--and a wet/dry vacuum to remove the dirt from the coils. This should solve the problem for you. Be sure to turn the breaker off and allow the unit to dry for a few hours before using it. Thanks for the question and reading my article.

You can find a good coil cleaner and instructions on this page:

https://axleaddict.com/rvs/RV-Roof-Air-Conditioner...


Eros 2 years ago

Hi Randy,

I got a rooftop Coleman mach 15,0000 BTU and last night while running the white wire coming out of the control panel connected to the rv got hot , what might be causing that?.


Randy Godwin profile image

Randy Godwin 2 years ago from Southern Georgia Author

Hello Eros, check the green wire--extra ground--to be sure it's properly connected in the junction box. Let me know if this helps or not.

Randy


Mikmar 2 years ago

I would like to replace a 1996 Dometic Quick Cool rooftop air conditioning unit on my rubber roof fifth wheel. The A/C system is ducted, with 16 round cold air outlets for 3 rooms in a 30+ foot long space with 2 slideouts, about 2000 cubic feet to cool, total.

The A/C "control box" (?) above the ceiling is a Dometic DuoTherm (Relay Kit?), PN 3104998. The number 3104998.004 also appears.

It also says "Dielectric Tested Okay," "use copper conductors only," and "20 amps," as well as 115 volts (alternating current), 60 Hertz, single phase.

It also says "for use with air conditioners" and "679; 690; 696; 600 series." The "control box" shows a serial number or SN of "E6285113." The rooftop unit shows a serial number of "62817506."

The thermostat in the interior is a "DuoTherm by Dometic" with a 40 degree F to 90 degree F range, a "heat-off-cool" selector switch, a "hi-lo" fan selector switch, and an "on-auto" switch. The electrical rating is "1 A Max, 30 V Max." The Part Number is "PN 3105058, Rev A" followed by "RSV420K62."

The "heat" selection controls a propane burner which is not part of the A/C unit. The propane burner doesn’t work (needs a new electric blower motor), and I don’t really trust propane burners anyway, so I have been using two plug-in ceramic heaters on the floor. Would a heat strip inside the A/C unit be advisable?

Can the rooftop unit be replaced by a Dometic Brisk II air conditioner designated as "B59516" (white, 15000 BTU)? Would a 13500 BTU unit be more than adequate? What control box is needed? Can the existing analog thermostat be used?

Everything seems to work. It just does not cool. The Quick Cool unit is not set up for recharging with refrigerant. How can I keep my replacement cost down? Is there a rooftop unit that would not require replacing the old control box and analog thermostat?

I am 60+ and have a tight budget. A neighbor can do the work if it doesn’t become too complicated. I prefer not to pay somebody $90 per hour to do the installation in order to keep a warranty. I don’t need a warranty as long as the odds are good that the replacement unit will actually work for a reasonable period of time.

Your advice would be welcome.


Randy Godwin profile image

Randy Godwin 2 years ago from Southern Georgia Author

Hello Mikmar, I'd think any AC designed for a ducted system would work as a replacement for your unit. Many of the ducted models should work okay with your present thermostat system, but if not, thermostats are relatively inexpensive to replace. And yes, a heat strip would do nicely in place of the propane heat source.

Feel free to ask me for more info if needed.

Randy


MikMar 2 years ago

Randy, Thanks for your response. Are you familiar with Dometic AC units? Is there a Coleman AC unit you would recommend that would probably work with my present analog thermostat? Should a competent handyman who is NOT trained in AC units (but has some limited experience with such units) be able to install it with reasonable odds of success? Is there a reason for me to prefer 15000 BTU to 13500? Should I get the heat strip from the manufacturer of the AC unit, or does it not matter? Should I expect to replace the old control box? Do I need to worry about the dimensions of the cut-out in the roof for either a Dometic or a Coleman AC unit? [Are they likely to have changed since 1996?] Thanks again.


Randy Godwin profile image

Randy Godwin 2 years ago from Southern Georgia Author

Yes MikMar, I'm very familiar with Dometic ACs. As far as I know all ac units use a 14 inch square opening for the installation.Also, a competent handyman should have no trouble at all installing new AC. It depends on the type thermostat you presently have whether it will be compatible with the new unit. The heat strip will be best be obtained by the make of the AC rather than a generic part if you can get it.

A 15000 is only preferable if a 13000 doesn't cool well enough. I hope this info helps but feel free to ask for more info if needed.

Randy


MikMar 2 years ago

Randy, Thanks once more. Where would you recommend I go to get reliable info regarding compatibility of my thermostat with new AC equipment (preferably Dometic, or maybe Coleman) rather than just trusting an inside salesman who prefers to sell me a complete package of new stuff (I prefer not to change thermostats)?


Randy Godwin profile image

Randy Godwin 2 years ago from Southern Georgia Author

I find most of my info and AC parts online, MikMar. There's a plethora of such places but you have to look closely at what they offer before purchasing parts from them. Try both Dometic and Coleman sites first if you prefer them. They should be able to furnish you with the parts you require. :)

Randy


MikMar 2 years ago

Randy, Thanks for your responses. I will try a second source for Dometic AC units. Over and out.


Kahuna528 2 years ago

Randy,thanks for the elucidation. I have a 29' 1991 Wilderness trailer and the Coleman just blows hot air. I'm looking for a new transplant that will accommodate the ceiling ducts. Any suggestions will be appreciated. Coleman model # 6759-723, serial 119008118. I'm not sure how this hub program works, I signed up, john.kole@comcast.net


Randy Godwin profile image

Randy Godwin 2 years ago from Southern Georgia Author

Hello Kahuna, you may find what you need at this link, especially if you peruse the models at the bottom of the page. I think any ducted AC will replace your old model fine.

You didn't have to join HubPages to ask or comment on this or other articles on this site, but welcome as a new member anyway. Feel free to ask for more info if you need it. :)

Randy


Randy Godwin profile image

Randy Godwin 2 years ago from Southern Georgia Author

Sorry Kahuna, I neglected to put the link in my last comment. Here it is:

http://www.amazon.com/Dometic-Penguin-Conditioner-...


ceferino 2 years ago

Hi randy my domestic turns on then runs when the temperature hits to where it needs to be it shuts off but the unit is humming when off what does this mean?


Randy Godwin profile image

Randy Godwin 2 years ago from Southern Georgia Author

@ceferino--Have you checked to see if the humming noise is coming from the compressor or the fan motor? Does the fan cut off too when the correct temperature is reached?

RG


ceferino 2 years ago

When it turns off the fan is off but the humming continues yes for about five min then it stop but what weird is when I turn off the switch to stop it completely it stays humming I have a 95 sunline anniversary edition 30 ft .


Randy Godwin profile image

Randy Godwin 2 years ago from Southern Georgia Author

It could be a capacitor going bad and having a difficult time storing a starting charge. If so, it will eventually not start the fan and/or the compressor depending on if you a capacitor for each of them or only one to start both of them. This is merely a guess at this point though. Anything else you can tell me?


ceferino 2 years ago

If we bump the wall it shuts if the thermostat is old lol but im wondering if that has to do with anything also and you have been a great help THANK YOU!


Randy Godwin profile image

Randy Godwin 2 years ago from Southern Georgia Author

An old thermostat can cause certain problems, ceferino. Perhaps you are due for a new one. :) Sorry to not be of much help to you with this problem, but thanks for the query. :)


ceferino 2 years ago

Anytime my friend anytime and yes you have been a great help , to not just me but many many others THANK YOU!


Lee 2 years ago

Randy, I have a Coleman roof mount unit like the one you have pictured, I don't know how old it is, it came with the camper when I bought it 8 yrs ago. My question is: The unit runs all the time, it blows cold air, but not like it used too, grant it, is has been very hot during the day here, so why won't it shut off when it gets cool or is it supposed to run all the time? Yes, I can here the compressor cycle on and off.


Randy Godwin profile image

Randy Godwin 2 years ago from Southern Georgia Author

Hi Lee,

I imagine the coils need a good cleaning if you haven't already done so. Not only do dirty coils make the AC work harder, they inhibit the air flowing across the compressor and fan and cause several problems. This includes causing the unit to run longer trying to reach the desired temperature. A good cleaning with coil cleaner will probably solve your problem. You can find it here:

http://www.amazon.com/SimpleAir-EZGA-Green-HVAC-Cl...

Randy


Lee 2 years ago

Thanks, I will give it a try........


Harry 22 months ago

Hi Randy, I have a coleman mach 1500, it is having trouble starting so I was going to replace the capacitor , however there seems to be 3 of them,

a large round one, a smaller oblong one and a small black one, not sure where to go with the change.


Randy Godwin profile image

Randy Godwin 22 months ago from Southern Georgia Author

Hi Harry, you can either test the capacitors yourself with an ohm meter or take them to an AC repair service and have them test them for you. If you have a digital meter you can do it yourself by setting the meter to ohms and observing if the random numbers fall steadily or not. If they stay the same value they are probably bad. Hope this helps you find the right cap. :)

Randy


Robert 22 months ago

how many btus is the coleman mach 3 model6759 - 723


Robert 21 months ago

how many BTU's is the coleman mach model 6759 763


Randy Godwin profile image

Randy Godwin 21 months ago from Southern Georgia Author

Hi Robert, I don't have the specs for ACs but the BTUs would be either 13,500 or 15,000 I believe.


Gus & The Bus 18 months ago

Well you have done it this time. With your pointers I will install a rooftop A/C on a 1990 Short School Bus. Be ready for some questions!!!!

Thanks in advance


Randy Godwin profile image

Randy Godwin 18 months ago from Southern Georgia Author

Bring it on, Gus! I'm always up for something different and challenging. :) Ill be awaiting your queries.

--RG


Robert Baker 17 months ago

Can i replace my Coleman ac unit (rooftop no duçts ) on my jayco jayhawk trailer . with a rooftop dometic ac unit in the same hole and use the Coleman inside parts as well


Randy Godwin profile image

Randy Godwin 17 months ago from Southern Georgia Author

Hi Robert, yes the same hole--14"x 14"--will work for all RV AC units. You don't need to use the old ceiling assembly as a new AC usually comes with a ceiling assembly included.

Randy


Robert baker 17 months ago

Mr Godwin , the unit that I'm getting does not come with inside parts . will my Coleman parts work. AC unit coming from eBay


Randy Godwin profile image

Randy Godwin 17 months ago from Southern Georgia Author

I really do not know, Robert. There are so many models of RV AC units made over the years that I'd just be guessing. Sorry I cannot help you with your question.

RG


Robert Baker 17 months ago

Randy that's OK . you helped me out alot thanks

    Sign in or sign up and post using a HubPages Network account.

    0 of 8192 characters used
    Post Comment

    No HTML is allowed in comments, but URLs will be hyperlinked. Comments are not for promoting your articles or other sites.


    Click to Rate This Article
    working