Rooftop AC Unit Replacement

j-d wrote:

Mbiallas wrote:
Well we have thrown in the towel on our old Coleman Mach unit.

Does the Old Mach still run? We were about to sell a 24 year old Class C with a 13500 Mach on it, just to sell it. Came across Chris Bryant's article on how to clean the coils and drain. Did that, and it got its cool back.

We bought another C with a Mach 15000 on it, cleaned the coils as Chris explained in the article, also pulled the motor and cleaned the indoor blower wheel (squirrel cage). That Mach is now 15 years old.

One thing I learned recently, again Shout Out to Chris, is that the back of the unit, the condenser coil, has to have its edges sealed to the shroud with air baffles. A little hard to explain, but the air over the condenser is drawn in from behind. It can't be allowed to get some of that air from the side vents of the shroud. Easy fix with some foam insulation for copper pipe.

We have cleaned the coils and they look great on both sides. I'm afraid the motor is nearly shot as I often have to climb on the roof and give it a hand starting while someone else hits the switch inside. I had hoped it was the capacitors but they were all replaced a few uses ago. As I understand the fan is supposed to pretty much free-spin when you touch it. Ours is tough to spin and most certainly stops dead as soon as you quit pushing it along. And now the compressor doesn't want to kick on at all.

We had planned on getting a new thermostat as well as a new unit. The current unit simply has a grate on the ceiling that holds the air filter and gives access to the wiring. Is there anything else we will need to purchase aside from the unit and thermostat? I read somewhere that there was some control module (not sure if that is the right name) that was needed but didn't come with the new unit. That person said they were able to pull it from their existing unit and it worked on the new one.

Also - will there be a noticeable difference between a 13.5k and 15k btu unit? Our camper is a 37 footer located in South GA. So we need all the cooling we can get.