Coleman Mach no work 2012 Navion 24j

[Tof]

Have Coleman Mach Model:48058-876 has stopped dead in its tracks. Can not reset. No digital display at thermostat. Power to coach, microwave, and to AC breaker checks OK with volt tester.

Wide open to any suggestions?

[Morich]

A point to keep in mind on the heat and air is that the thermostat uses 12VDC as only acts as a switch to turn the 110AC on/off.
When there are no lights, etc. at the thermostat, I tend to think of 12VDC problems!
The issue is a design thing where the big air unit needs lots of power and we get it from 110AC. But those heavy wires are not nice to fit a half dozen or so into the little box on the wall. So they use little wires and power at the thermostat to control a big relay up on the AC unit where they start and stop the big wire 110AC!

If we know what year, make and floorplan you might have, there are often online drawings where we can sort out which breaker or fuse might be involved!

Maybe do a quick test to see if the furnace will start the blower when the thermostat calls for heat. Just as a generic idea, the 12Volts from the furnace may run the thermostat for both heat and cool. If the furnace blower doesn't come on right away after setting for heat, maybe a check in the "load center" where a bunch of 12Volt fuses are located may turn up one labeled for furnace?
Click this snip for better view!


Tell us which RV if we need to chase it further?
Consider this a first shot random guess!

[Tof]

First of all the contact cleaner on the fuse was a bust. No joy! Played with the furnace. It won't run gas or HP. Pulled Furnace fuse and reset. Now display but still nothing works.

I happened to note your location. My Uncle Clifford had his first teaching and coaching job there after San Marcos State. The football team had no practice field so they used local ranchers Goat pasture.

Back to problem, next move DR.

[Tof]

Have checked settings and wire terminations on the thermostat. Red wire has power. when you move the controls to fan or any other position nothing happens or no current. Since this old one is not an electrical genius how do we determine a faulty thermostat?

[Morich]

I try to go the easy way when it seems as good as the hard way. When faced with looking at an air unit which may be on the roof or a furnace which is down where I can get to it, I look at the furnace as the easy one!
so if we move into looking at the furnace, can you locate a label on the furnace that tells what brand and model it might be?
As an alternate, do you have booklet for the furnace in a bag of books for the RV? That might also tell us what we need.

As background info, the idea is that the power wires from the batteries to the furnace fuse and then it also goes on different wires to the thermostat. The thermostat acts as different switches by the way we set it. When we set the thermostat to heat, The power you are seeing comes from the heater to to the thermostat. When the temperature calls for heat, that power is sent back to a board on the furnace to make the blower start running.
I don't know the furnaces all well enough to tell you where to look for that power coming back. We know 12volt is good and getting to the thermostat, but we don't know why it is not making the furnace fan come on!
If we can locate the right manual for the brand and model of furnace, we can then likely find a drawing to show where to look at the power coming back!

Maybe think of it this way as we do it more?
We have a switch on the wall and we know power is getting to that switch but the light doesn't come on like we expect it when we turn on the switch!
So we have to find out if the wire is bad or if the power is getting back and maybe the bulb in the light is bad!
Only in your case the switch is a thermostat and a blower on the furnace instead of the light bulb!

OR?
If not finding the furnace info, does the thermostat have any brand or model where we might look for a manual for it?
The connections are often not marked to tell us which wire does each thing but maybe we could find a book with that info?

[Tof]

The coach is a 2012 Navion 24j
Ac is a Coleman Mach Model 48058-876
Thermostat is an RVComfort.HP Mach 8530-3381 Digital Heat Pump RV Thermostat. Which by the way wouldn't you just know it is discontinued?
The Ceiling Control box is 8530B7332

[bigb]

Originally Posted by Tof

Have checked settings and wire terminations on the thermostat. Red wire has power. when you move the controls to fan or any other position nothing happens or no current. Since this old one is not an electrical genius how do we determine a faulty thermostat?

Have you pulled it off the wall and checked all the connections and all the wires? You say you got the display to come back, but when you try to switch to a cooling or heating mose does that display go dark again?

I would be looking at the connections, especially the ground connection. I have that same thermostat a year older than yours, it's a pretty simple device and it has been pretty bulletproof, there is not that much that can go wrong with it which makes me suspect a connection issue.

[Morich]

Well, this is not good! I've run the thermostat number down to this site for manuals but not getting any good info:
https://library.coleman-mach.com/
When scrolling down to the correct model and hitting download, it simply takes me in a circle back tot eh same page!

I'm not sure what to make of that. Is the page being rebuilt? Is the info dropped for some reason or did the company decide totally to ignore the issue?

I have to say I am now totally at a dead end without being able to get info. Certainly no heat and air guy but normally just have to go in and study the way it works but without the manuals and info, I'm dead!

Sorry, but I think I'm no help!

[Tof]

Will pull that little jewel off of the wall first thing in the morning, open each connection and spray well with contact cleaner.
To be honest have not observed the display when switching. Will check that also.

[bigb]

Originally Posted by Tof

Will pull that little jewel off of the wall first thing in the morning, open each connection and spray well with contact cleaner.
To be honest have not observed the display when switching. Will check that also.

If the display goes dark when you try and switch something on you have a bad connection on the power or ground (or a dead house battery, you did check for 12 volt power in the coach right?).

Also look in your manual packet, mine has a brochure for the thermostat. I don't recall if it covers installation or if it's just a user manual though.

[bigb]

This covers the 8530 series