Installing/swapping Coleman Mach thermostat in my RV

Question

I've got a 2008 Four Winds Chateau 31P Class C RV. I think my thermostat is faulty. Sometimes the AC turns on, sometimes it doesn't. I've got another similar RV and when I slide the temperature control knob back and forth I can hear a "click" noise when it crosses over the current temperature (...turns the AC on/off when it gets to the right temperature....same for when the furnace is running). On this (presumably) faulty Coleman Mach thermostat in my 2008 RV I do not hear such a click.

Does anyone out there have a Coleman Mach thermostat...can you tell me is you hear a "click" as you slide the temperature knob back and forth? For example...let's assume it is 80 degrees inside the RV. If you turn on the AC but the thermostat temperature slide is on 90 degrees your AC should not turn on. BUT, as you slide the control down past and below 80 degrees do you hear a "click" on the thermostat and then your AC turns on?

I'm assuming (hoping really) that it is just a faulty thermostat. I have ordered the exact same Coleman Mach to replace it. There are 6 wires coming out of the wall and connecting to the thermostat. I assume replacing it is as easy as matching up the wiring and connecting the new thermostat. This is 12v tiny gauge wiring. I'm very familiar with splicing/connecting regular 120v wiring with wire nuts/etc. But these wires are tiny and look delicate. What do you recommend for splicing these wires together to connect the new thermostat? Is there a special crimping device? Do you use tiny wire nuts? Any suggestions?

Thanks in advance for you help!!

-Chris

old-biscuit · Answer

Remove t-stat cover from base plateTake a picture of wiring connections so you know which wire goes whereRemove wires from terminals by loosing the screws

joe417 · Answer

My home thermostat went bad with the same symptoms recently.

The click you hear(or should hear) is the relay opening or closing. We have a similar coleman thermostat in our 5th W.

I put a digital in out TC about 2 years ago. Much better thermostat than the Coleman. Unfortunately, you already ordered the same thermostat as a replacement. It works.

As far as matching the wires, Old-Biscuit supplied the wiring info. That's a fairly standard color code but rv manufacturers don't necessarily worry about the color.

If it is like my coleman, you may need to write down or take a picture of the wiring. My coleman has the color coded wires coming from the thermostat and attaching to different color wires, with wire nuts, about 6" inside the wall.

ksg5000 · Answer

Clicking noise is usually associated with analog thermostats - many RVers toss those and upgrade to digital thermostats which tend to be more accurate.  I switched mine analog Coleman for inexpensive digital Honeywell ... lots of threads about converting to digital thermostats.

j-d · Answer

Our new home thermostat is a digital Honeywell and it clicks as the temperature reaches the set point. Say it's 90 in the coach, you want 80 so you select A/C (vs Heat) and move the temp control toward 80. By "move" I mean Slide if Analog, Push Button if Digital). As the set point approaches 80, it'll click to start the system. Once it IS 80, it'll click again to stop the system. "System" being Fan and Compressor if that's how it's set up (Auto Fan), or Compressor only (set up for Fan On).

sj-chris · Answer

The Coleman Mach thermostat I have has the 6 wires soldered directly onto the circuit board (no screws).  If the new thermostat arrives with 6 wires that need to be connected to the 6 wires currently connected to my existing thermostat I will have to cut the wires and connect them.  I am very familiar with working with larger gauge 120v wiring and connecting wires with wire nuts/etc.  These 12v wires look tiny.  Do people recommend small wire nuts for making the connection?  Or are there some special crimp connectors I should know about for such small wiring?  Let me know your thoughts.  Thanks!

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Installing/swapping Coleman Mach thermostat in my RV

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