Comfort Master APU: Check oil switch?

Thanks,Flightline! I will try to work with the info you gave me , I think it will do it.@ Gears- happens to me all the time , I think it is computer glitch/problem.I do the same - removing it from the batteries for a comp. reset . Still doing it thou.

 

The display on my unit took a dump. I've googled for quite some time, trying to find one, new or used with no luck. I wouldn't be pursuing this so hard, but I replaced the motor and there's less than 30 hours on it.

Looking for options

Looking for solutions.

 

I've re-read this thread and am coming to the realization that it may be in my best interest to wire around the ecm and bypass all the comformaster electronics. I think I can look at the wiring diagram that was posted and get that figured out, but what does a guy use to turn on/off and regulate the air conditioning?

 

Use a house thermostate controling a couple of relays. One for the blower. The cool side of the thermoste to a relay controlling the compressor. Use a thermostate with a compressor delay built in, most are.
I initally tried running the compressor nonstop with the blower on high. It would cool really great for about 2-3 hours till frosting up the evaporator. Then installed it on a thermoste and worked great without freezing up.
I also wired the engine fan on the same relay as the AC compressor.
The fan in the bottom of your unit, needs to run all the time as to remove heat out of the box.

 

OK gents, here's my predicament...

It's either shell out $550 bucks for a new CPU and keypad or bypass all that stuff as some of you have done. First of all, good or bad idea to replace the CPU and keypad?

I'd like to bypass. Really would. If I can have thermostat in the sleeper for the A/C and such, and be able to start and run the unit from the bunk, that'd be awesome.

I need to decide and commit to one or the other as it's getting pretty warm outside already.

Those that have bypassed, do you have step by step procedures with pictures and a specific parts list? I'd even be willing to shell out some $$ for this information IF IT WORKS.

 

I was going to tell you about the guy selling them on Ebay, but you found them by the sounds of it.

Whatever you do, don't throw out your old controller. I would love to have an old one to disassemble and reverse engineer. I have been contemplating building a custom control for these for a while now. This thread about by-passing has inspired me more.

So far mine's still working fine aside from the few quirks and bugs that it came with, but I fear it might go the way of yours. Not to mention there are several bug fixes and features I'd love to see in them.

I wish I could get the specs on all the sensors and code for the controler. It would be no problem to build one then, but it looks like I'm going to have to go the way of reverse engineering and trial/error. So, having an old controller to play with would be helpful even if it's shot. Ideally I'd love to have a whole unit as a test system so I can leave mine alone until it's ready, but the less I have to screw with mine while it's still working the better.

 

Does the CM controller run the compressor nonstop until it hits the shutoff temp? Seems to me it does, I would think it would need to cycle like a typical auto AC does as the pressure changes.

 

Yes the controller runs the compressor nonstop as long as the cpu is calling for coolness. Most older vehicles we're set up this way. It will cool better and better on the compressor. This type of system uses the expansion valve to releive pressure. The AC clutch will last longer. I belevie using an expansion valve enstead of an orfice works better. Wish I knew why newer vehicles got away from it.

 

I never knew that, learned something. Just shows my lack of knowledge on the cooling system. The expansion valve is the block that's on the lines coming out of the evap isn't it? Well, that does make it a lot simpler to control though. It does control the radiator fan though, not sure if it's just based on engine water temp or AC as well.

I've also noticed that the controller delays the compressor for about 2min after start up. That is excessively long IMO when the engine is warm. That's a long time to wait for cold air on a hot day if you shut it off and restart it.

 

Yeah , I join you on that , if any of you guys got info about it , with pix , I join Gears and I am willing to shell some money towards such effort.