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Replacing Coleman 6536 Series AC with a Split System - Printable Version

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Replacing Coleman 6536 Series AC with a Split System - rickj - 06-01-2025

We purchased Coach #538 March 2011 from Newel Mortorcoach (we concluded that the premium charged by Newell Motorcoach for the coach was well worth it compared to the inherent maintenance issues with most FSBO coaches). Over the years we had to replace compressores, blower motors,  circuit boards and pillow bearings multiple times. In 2023 the passenger side Coleman was completely rebuilt and that was the last straw which prompted an analysis and research for alternative air conditioning solutions. It became evident that a split system would prove to be the most durable and reliable system; the problem of course was space. The research and advice that was sought out turned out to be a rather torturous process; the reason being that there was not a lot of technical knowledge within the residential HVAC community (they all were proficient only in plug and play installations-as soon as they were presented with the challenge of building a custom system with components from disparate manufacturers the HVAC contractors knowledge base vaporised). Accordingly I initially ended up with a system that would not work as the air handler and condenser were mismatched (although I had been assured that the system would work) since the condenser was an inverter communicating unit and therefore would not work with the basic air handler that had been installed.
Overview:
Please note that this is a review of an installation and rebuild of the drivers side AC basement; also this is a 2T system using, the now outdated, 410A refrigerant. The air handler was the controlling device as it had to fit the space, i.e. had to fit in the basement height and also had to be oriented to have a return utilizing the plenum (air return) cavity that is already in place and in addition have the ability to connect the discharge to the internal air duct. We chose a Goodman AWST air handler, however it required substantial modification to fit in the basement; it also required modification of the plenum. Once the Coleman AC unit was removed it was decided to rebuild the entire basement since it was apparent that modification and rebuilding/strengthening the plenum box was necessary. The air handler was cut down to a height of 29 inches to accommodate the height restriction and the blower was replaced so it could be reconfigured to accommodate a side discharge towards the duct that runs down the spine of the coach. As previously stated the condenser that was installed was mis-matched (this was a Goodman GSXS with a Goodman GTST thermostat) and therefore the system would not work. Again, another learning curve to ascertain what type condenser would work with the AWST air handler (changing the air handler was not an option as no other air handler that was researched could be cut down as described above). During this phase of research and learning a contractor friend recommended a HVAC mechanical contractor and this proved to be invaluable.  Mechanical contractors by their nature are accustomed to building and modifying custom HVAC systems; this particular HVAC mechanical contractor actually enjoyed the challenge, which facilitated completion of this project. We ended up using a thru-the-wall condenser, a NCP 4244. This also had the advantage of improving our design as it could be bolted to a Morryde sliding shelf thus allowing access to the air handler, 220v wiring and the plenum itself for maintenance and repair ( a feature that originally had been desired but could not be accommodated due to height restrictions). In addition we used no kink flexible refrigerant lines to facilitate the movement of the condenser as it is pulled out on the sliding tray. To finish the set up a standard Nest thermostat (not the leaning thermostat) was used as we could employ it to not only control the AC but also use the same thermostat to control the  Aqua Hot heat (note that the AC power to the thermostat is 24v ac and therefore a transformer changing to 12v dc was added to the Aqua Hot boiler at the relay)  in the bedroom where this thermostat is located. The system now blows cold strong air thru all the wall ducts which the Coleman did not and the split system should ensure many years of reliable air conditioning. Note that the one remaining phase of the project is to open up the basement door with a larger cut out for air flow so the condenser can draw in cool air and discharge hot air. The link to the pictures documenting the drivers side  AC rebuild (copy and paste into your browser): https://photos.app.goo.gl/g3brkdB9diU8AJ7x9

RE: Replacing Coleman 6536 Series AC with a Split System - smagown - 06-01-2025

Nice job, Rick.

RE: Replacing Coleman 6536 Series AC with a Split System - HoosierDaddy - 06-01-2025

Wow! Thanks for sharing a detailed write up on a very worthwhile upgrade!

RE: Replacing Coleman 6536 Series AC with a Split System - rickj - 06-02-2025

(06-01-2025, 06:11 PM)smagown Wrote:  Nice job, Rick.

thank you
(06-01-2025, 08:21 PM)HoosierDaddy Wrote:  Wow! Thanks for sharing a detailed write up on a very worthwhile upgrade!

thank you

RE: Replacing Coleman 6536 Series AC with a Split System - 360 - 06-02-2025

Incredible upgrade, especially the unit being on a slide!

My new to me coach had two new Coleman Mach 6535-380's put in about a year and a half ago. Can't believe how much quieter they are than the SCS units. My ducting is also a bit different so I think that's part of the equation as well.

RE: Replacing Coleman 6536 Series AC with a Split System - rickj - 06-02-2025

(06-02-2025, 10:38 AM)360 Wrote:  Incredible upgrade, especially the unit being on a slide! 

My new to me coach had two new Coleman Mach 6535-380's put in about a year and a half ago.  Can't believe how much quieter they are than the SCS units.  My ducting is also a bit different so I think that's part of the equation as well.
(06-02-2025, 10:38 AM)360 Wrote:  Incredible upgrade, especially the unit being on a slide! 

My new to me coach had two new Coleman Mach 6535-380's put in about a year and a half ago.  Can't believe how much quieter they are than the SCS units.  My ducting is also a bit different so I think that's part of the equation as well.

thank you; just got tired of those Colemans, bad design. this should provide a better experience.

RE: Replacing Coleman 6536 Series AC with a Split System - rickj - 06-02-2025

(06-01-2025, 06:11 PM)smagown Wrote:  Nice job, Rick.

thank you Steve. I think I know you? We visit my wife's relatives in West Monroe every year.

RE: Replacing Coleman 6536 Series AC with a Split System - Jack Houpe - 06-03-2025

You did a great job thanks for all those pictures! I found out the information that the condenser gets from the evaporator is very complex, it equates to a series of bursts of different DC voltage with signals of pulse width modulation which tells the condenser to speed up fan or compressor or both and is way over my head thats why I chose to use evaporators of the same make as condenser but you've gone the extra mile making a mixed unit work. thumbs up!

This is an inverter unit is it not?

RE: Replacing Coleman 6536 Series AC with a Split System - smagown - 06-03-2025

Rick, we've met before, I grew up with Penny also.

RE: Replacing Coleman 6536 Series AC with a Split System - rickj - 06-05-2025

(06-03-2025, 04:20 AM)Jack Houpe Wrote:  You did a great job thanks for all those pictures! I found out the information that the condenser gets from the evaporator is very complex, it equates to a series of bursts of different DC voltage with signals of pulse width modulation which tells the condenser to speed up fan or compressor or both and is way over my head thats why I chose to use evaporators of the same make as condenser but you've gone the extra mile making a mixed unit work. thumbs up!

This is an inverter unit is it not?

it is not an inverter unit; wanted to keep it simple, just two 'dumb' units. Also, the inverter communicating condenser will not work with the air handler I am using(and the air handler choices were severely limited as it had to fit in the basement, in particular the basement height of 29" so the air handler had to be cut down and this is the only air handler I found that could be modified as to height, exhaust orientation, etc).