Air Conditioner Description & Operation

Shane826 · 07-17-2016, 06:52 PM

As a mechanic, one of my favorite bits of info is the "description & operation" section of the service manual. It's a lot easier to figure why something doesn't work if you know how to SUPPOSED to work...

That said, what is the operation sequence for the air conditioner? I'm pretty sure I have a Coleman 13,500 unit. I had the inside portion down during the spring to clean it out and make sure everything works. The compressor wasn't kicking on but I thought it was a bit chilly so it didn't surprise me. There is a copper wire in the duct work; I heated that with a butane crack torch and the compressor kicked on and the unit blew ice cold air... Our first camping trip didn't require any A/C but this past weekend sure was warm in the afternoon. And the A/C didn't cool at all. Compressor never came on but the fan runs full blast. Luckily it got pretty cool at night.

So what are the parameters for the A/C to come on?

Shane826 · 07-17-2016, 09:36 PM

Another quick stupid question... How does the A/C shroud come off? I really hope I don't have to drill out these rivets!

Padgett · 07-17-2016, 11:12 PM

My Coleman just had three big screws (one front, two in the blower grille). See pic.

Also enclosed are the schematics of the roof unit and the air handler.

**Bill** · 07-18-2016, 06:23 AM

Just a thought re picture number 1. When I pulled the shroud off my airco a couple years ago, those three screws were quite tight. Of course they are supposed to be tight, so they don't work loose while traveling. We've all seen escaped shrouds lying beside the road at one time or another, and they are expensive to replace. So when I put the screws back, I used a bit of blue Loctite on each one. And to aid removal next time (if there ever is a next time), I used a Sharpie to write "Loctite" on top of the shroud, with 3 arrows pointing to the 3 screws.

Bill

[email protected] · 07-18-2016, 06:55 PM

Quote:

Originally Posted by Padgett

My Coleman just had three big screws (one front, two in the blower grille). See pic.

Also enclosed are the schematics of the roof unit and the air handler.

It says Phillips head screws....mine had star head screws in them....don't know if they changed these out after 2003 or maybe it was something the previous owner did.
Tom

Padgett · 07-18-2016, 09:04 PM

Your Mileage May Vary (YMMV)

Shane826 · 07-19-2016, 10:42 AM

Ok I took a look at my capacitors, they don't look melted like some of the pics I've seen here. Not sure where to go next or what to test? I'm gonna need A/C QUICK! Help! If anyone thinks it would be easier to discuss via phone, PM me and we can set something up. Thanks!

PS- Model number is 9203C876, says Coleman Mach on top of the shroud.

Padgett · 07-19-2016, 11:44 AM

Well first you have to know how to work around 120vac. If not find someone who does. A shock could knock you off the top of the trailer.

If so buy, rent, or borrow a DMM that can read capacitance like a MS2018A (or hire/cajole someone who has one & understands working with AC power).

Now the first check can be done from inside the coach. When you turn the AC on COOL do the lights dim momentarily ? If not the compressor is probably not getting power.

Drop the plenium so you have access to the controls. Turn the AC to LO COOL. Do you have 120VAC on pins 1 and 3 of the big connector (see schematic I sent earlier). If not the problem is in the lower unit. If OK you need to go up top.

If no dimming you probably have an open circuit somewhere & it is hard for a capacitor failed to do that. Note that the fan and the compressor each have their own circuits so can have fan and no compressor.

I sent a copy of the schematic and just need to trace the circuit until you find the bad connection and hopefully it is not inside the compressor.

Shane826 · 07-19-2016, 12:03 PM

Well, here's where it gets weird. I popped the front shell open and turned on the A/C. Sure sounded like the compressor kicked on... Went outside, up the ladder, and felt the compressor. Running good. A/C lines are cold. Went back in, blowing cold air...

So the system WORKS. But I feel like it's "seeing" something that is inhibiting the compressor. Keep in mind I'm an auto mechanic, so I'm going off all the parameters the car has to see to allow A/C.

Modes this have a thermostat? What is that bare copper wire I heated to get the A/C to come on back on that chilly night? There is a lot more sun today than when we were camping; our site was in the shade.

Craigrrr · 07-19-2016, 12:45 PM

You may have a loose connection on the capacitor I would look there if all is good NOW