Overview
Coleman Mach two-stage systems have two AC compressors on a single zone. This gives your RV more cooling power by running one or both compressors depending on demand.
These systems use relay-based wiring with two connectors:
- 9-pin connector - Same as other Coleman models (power, ground, heat wires)
- 3-pin connector - Additional power and furnace control
1 Identify Your Wiring
Turn off power and remove your existing thermostat. You will find two connectors behind the wall plate.
9-Pin Connector
The 9-pin connector is the same as other Coleman Mach models. It carries power, ground, and heat control wires.
3-Pin Connector
The 3-pin connector provides additional power and furnace control for the second stage.
| Pin | Function | Description |
|---|---|---|
| R0 | 12V DC Positive | Second +12V power supply |
| R | 12V DC Negative | Second ground wire |
| W | Furnace Control | Furnace relay control wire |
2 Mount the WalTech Base Plate
Use the included mounting template, screws, and wall anchors to secure the base plate to the wall. The WalTech base plate fits standard thermostat mounting holes.
Feed all wires from both connectors through the opening in the base plate before securing it.
3 Connect to WalTech
Connect the wires from both connectors to the WalTech Vision 2.0 using the pin layout below.
Power
| WalTech Pin | Connection | Notes |
|---|---|---|
| Pin #7 | +12V DC | Both connectors' positive wires joined together |
| Pin #8 | Ground | Both connectors' negative wires joined together |
Heating
| WalTech Pin | Connection |
|---|---|
| Pin #5 | Heat 1 |
| Pin #4 | Heat 2 |
| Pin #3 | Heat 3 / B&O (optional) |
Air Conditioning
| WalTech Pin | Connection |
|---|---|
| Pin #2 | AC-1 (Compressor 1) |
| Pin #1 | AC-2 (Compressor 2) |
Freeze Sensors
| WalTech Pin | Connection |
|---|---|
| Pin #11 | Freeze Sensor 1 |
| Pin #15 | Freeze Sensor 2 |
Fan
| WalTech Pin | Connection |
|---|---|
| Pin #13 | High Fan |
| Pin #14 | Low Fan |
For heat pump systems, connect only the High Fan wire to Pin #13. Cap off the Low Fan wire separately with a wire nut.
Jumper Method for Fan Wiring
Insert a jumper wire into both Pin #13 and Pin #14. Use a wire nut to join both jumper ends to the original HIGH FAN wire. Cap off the LOW FAN wire separately with its own wire nut.
4 Power On
Snap the thermostat onto the base plate and secure it with the tightening screw. Restore power to your RV. The WalTech Vision 2.0 should power on and display the setup wizard.
5 Configure Your System
In the setup wizard, select "Coleman Mach Two Stage Thermostat" as your system type.
With a two-stage system, both ACs can run individually or together. You can configure a stage gap (0 to 10, adjustable in settings) that controls how many degrees apart the two compressors start. For example, a stage gap of 3 means the second compressor will not kick in until the temperature is 3 degrees above your set point.
Frequently Asked Questions
What is a two-stage Coleman Mach system?
A two-stage system has two AC compressors on a single zone. This gives your RV more cooling power by running one or both compressors depending on how much cooling is needed. The two compressors can start together or with a configurable stage gap.
Do I need freeze sensors for the two-stage system?
Freeze sensors are recommended but not required. If your system does not have freeze sensors, you can bypass them by using a jumper wire from Pin #11 to Pin #15 on the WalTech.
Can I run both compressors at the same time?
Yes. The WalTech Vision 2.0 lets you run both compressors individually or together. You can set a stage gap (0 to 10) in the settings to control how quickly the second compressor kicks in after the first one starts.
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