Coleman Mach Thermostat Wiring Guide

 If you own a Coleman Mach air conditioning system and need to install or replace a thermostat, understanding the wiring process is important.

The RV thermostat serves as the control center for your vehicle air conditioner, allowing you to set the desired temperature and regulate the cooling process.

In this article, we’ll walk you through a step-by-step guide on how to properly wire your Coleman Mach thermostat, ensuring your RV HVAC system functions optimally and efficiently.

How to wire a coleman mach thermostat

IMPORTANT: I want to be as simple as possible for everyone to understand. But for the standard wiring diagrams, please see them near the bottom of this wiring guide.

The easiest way to wire a  Coleman mach thermostat is to cut the wires after the wire harness and simply connect the wires from your thermostat to those cut as you can see in the following image.

Read also: Emerson thermostat Wiring

That way you won’t have to study what wire colors go on what wire colors, you will just match up the wires based on the colors and you will be good to go.

Another way to wire your Coleman Mach thermostat; If you have wires like in the image below, connect the wires as follows.

• The blue wire from the thermostat bundle it up with the large white wire and a blue wire from the wall.

• The gray wire from the thermostat attach it to  the smallest white wire from the wall.

• The green wire goes onto the green wire.

• The white wire from the thermostat goes on the medium white wire from the wall.

• Yellow from thermostat goes onto red and red from thermostat goes on red or brown wire if you are a a brown wire. And wire the reset as in the image.

Coleman rv thermostat wiring color code

The following table shows the common coleman thermostat wire colors and their functions. You may have more or less but these are the most common ones.

Thermostat Terminal	Color Designation	Function
R	RED	(-)12VDC SUPPLY
B	BLUE	(-) 12VDC SUPPLY WIRETO THE THERMOSTAT
Y	WHITE	COMPRESSOR CONTROL
GH	GH	HIGH FAN CONTROL WIRE
GL	GL	LOW FAN CONTROL WIRE
W	W	12VDC (+) FURNACECONTROL

The following chart shows the different electrical connections made by the thermostat during

operation to help you understand what each wire does in the process of cooling or heating.

Thermostat Operations	Internal 12VDC(+) Connections Made
Cool Mode Selected On High Fan	Red “R” to Yellow “Y” and Green “GH”
Heat Mode Selected On Any Fan Speed	Red “R” to White “W”
Cool Mode Selected On Low Fan	Red “R” to Yellow “Y” and Gray “GL”
Fan Only Selected (Hi-Fan Only)	Red “R” to Green “GH”

Where is coleman mach thermostat fuse located?

The fuse in a coleman mach thermostat is located right behind the thermostat. See image below showing the location of the fuse.

Thermostat control wiring For Ceiling Plenums With Individual relays

6799-720 & -726 SERIES, 7330-720 & 726 SERIES CEILING PLENUMS

The following table shows the thermostat control wiring, ceiling assembly wiring destinations, and relay functions for air conditioners with control boxes containing individual relays.

THERMOSTAT	CEILING PLENUM WIRE	UNIT OPERATION
YELLOW	YELLOW	COMPRESSOR RELAY
GREEN	GREEN	HIGH FAN RELAY
GRAY	GRAY	LOW FAN
BLUE	BLUE	N/A
WHITE	WHITE	FURNACE OR HEAT ELEMENT

6799-730 SERIES CEILING PLENUM

THERMOSTAT	CEILING PLENUM WIRE	UNIT OPERATION
YELLOW	BLACK	COMPRESSOR RELAY
GREEN	GREEN	HIGH FAN RELAY
GRAY	GRAY	LOW FAN
BLUE	BLUE	N/A
WHITE	WHITE	FURNACE OR HEAT ELEMENT

Coleman thermostat wiring diagrams

7330-730 & 8330-733 Series Cool Only Ducted Ceiling Plenums

7330-735, 7330-736 & 8330-735 Series Heat/ Cool Ducted Ceiling Plenums

7330-720 & 8330-723 Series Cool Only Remote Free Delivery Ceiling Plenums

7330-725, 7330-726 & 8330-725 Series Heat/Cool Remote Free Delivery Ceiling Plenums

Troubleshooting coleman Mach thermostat After Wiring

No low fan operation

 Start by checking for the 12 VDC between GL and B at the low voltage terminal strip in the ceiling assembly.  If there is voltage, check the voltage  between the thermostat’s  red and blue wires so it does not restore the voltage.

Furnace not working

Check for 12 VDC between the white and the blue wire at the thermostat. If there is voltate then the problem is probably not with the thermostat. If there is not voltge, you might want to check for 12 VDC between the blue and red wire. If there is not voltage, your may have a blown fuse.

Read also: Carrier infinity thermostat wiring

Final thoughts

To wrap up, that is all there is to Coleman Mach Thermostat Wiring. Tried to make it as simple and easy for everyone, even a beginner to understand. 

I hope you have managed to wire your thermostat after going through this guide. If not it’s perhaps a good idea to see call a mobile technician to help with the wiring