9330C755 Coleman Mach 15 RV Air Conditioner Controller | Hot Standby Component

9330C755 Coleman Mach 15 RV Air Conditioner Controller – Hot Standby Component

The air conditioner controller (also called the control box or relay board) is the electronic module that manages all functions of your RV rooftop air conditioner. It receives signals from the wall thermostat and controls the compressor, fan motor, heat strip/heat pump, and fan speed. When the controller fails, your AC may not cool, not heat, the fan may not work, or the unit may not respond to thermostat commands at all.

This 9330C755 replacement controller is designed for Coleman Mach 15 RV air conditioners with heat pump or heat strip capability. It’s a direct replacement for the Coleman 9330C755 controller and includes all necessary wiring and mounting hardware.

Compatibility

• Coleman Mach 15 (15,000 BTU) air conditioners: 48004, 48008, 48054, 48058, 48204, 48208
• Coleman Mach 3 (13,500 BTU) with heat strip: 7330, 7332, 7335, 7337
• Coleman Mach 8 (13,500/15,000 BTU) heat pump: 47004, 47008, 47024, 47028
• Coleman Mach 10 (15,000 BTU) heat pump: 45004, 45008
• Coleman RoughNeck series air conditioners
• Replaces part numbers: 9330C755, 8330-3451, 8330-3452, 9330-7551, 9330-7552
• Works with Coleman analog and digital wall thermostats (4-wire and 8-wire)

Specifications

Installation Guide

1. Safety first: Turn off 120V AC power at the circuit breaker. Turn off the generator if running. Also disconnect 12V power at the battery (the controller uses 12V for thermostat communication). Allow the AC unit to cool completely.
2. Access the controller: From inside the RV, remove the air conditioner ceiling assembly (inner shroud) by removing the 4 mounting screws. Lower the assembly carefully. The controller is typically mounted inside the ceiling assembly, near the wiring harness.
3. Document connections: Take detailed photos of all wiring connections before disconnecting. Label each wire with tape if needed. Note the position of each connector on the old controller.
4. Disconnect wiring: Unplug all wire harness connectors from the old controller. This includes:
   • 120V AC power input (black, white, green)
   • Compressor output (to rooftop unit)
   • Fan motor output (high/low speed)
   • Heat strip/heat pump output
   • Thermostat wires (4 or 8 wires)
   • 12V DC power (for thermostat)
5. Remove old controller: Unscrew the 4 mounting screws holding the controller to the ceiling assembly bracket.
6. Install new controller: Mount the new 9330C755 controller in the same position. Secure with the 4 mounting screws.
7. Reconnect wiring: Plug all wire harness connectors into the corresponding positions on the new controller (refer to your photos). Ensure all connections are secure and properly seated. Double-check the 120V power connections — black to hot, white to neutral, green to ground.
8. Reassemble: Lift the ceiling assembly into position and secure with the 4 mounting screws. Ensure the assembly is flush against the ceiling and all gaskets are properly seated.
9. Test operation: Restore 120V AC power and 12V DC power. Set the wall thermostat to COOL mode and lower the temperature. Verify:
   • The fan starts (high or low speed as selected)
   • The compressor starts (you’ll hear it click and the unit will vibrate slightly)
   • Cool air is discharged from the vents

   Then test HEAT mode (if equipped): Set the thermostat to HEAT and raise the temperature. Verify the heat strip or heat pump activates and warm air is discharged. Test FAN ONLY mode as well. Let the unit run for at least 15 minutes in COOL mode to ensure stable operation.

Common Symptoms of a Bad AC Controller

• AC doesn’t respond to thermostat commands at all
• Fan runs but compressor won’t start (no cooling)
• Compressor runs but fan doesn’t (can damage the compressor)
• AC cools but doesn’t heat (heat strip/heat pump not working)
• Fan only works on one speed (high or low relay failed)
• AC runs continuously without cycling (thermostat signal not being received)
• Clicking sounds from the ceiling assembly but no operation
• Burning smell or visible burn marks on the controller board
• Circuit breaker trips when AC is turned on
• Thermostat display is blank or unresponsive (12V power from controller failed)

Frequently Asked Questions

Q: How do I know if my controller is bad or if it’s the thermostat?

A: To isolate the problem, first check the thermostat: (1) Verify the thermostat display is lit and responsive. (2) Try changing modes and temperatures — you should hear relays clicking in the ceiling assembly. (3) If you have a multimeter, check for 12V DC at the thermostat terminals (red wire should have 12V). If the thermostat has power and you hear clicking but the AC doesn’t operate, the controller is likely bad. If there’s no 12V at the thermostat, the controller may not be supplying power. You can also test the controller by directly applying 120V to the compressor and fan terminals (bypassing the controller) — if they work, the controller is bad.

Q: Can I use this controller with a non-Coleman thermostat?

A: This controller is designed to work with Coleman 4-wire analog and 8-wire digital thermostats. While it may be possible to adapt other thermostats, we recommend using a Coleman-compatible thermostat for proper operation. If you want to use a different thermostat (such as a smart thermostat), you may need an adapter module or a different controller. Contact our technical team for compatibility advice.

Q: What’s the difference between 9330C755 and 8330-3451?

A: The 9330C755 and 8330-3451 are essentially the same controller with different part numbers for different production runs. The 9330C755 is the newer version that replaces the 8330-3451 and 8330-3452. Both controllers have the same functionality, wiring, and mounting. The 9330C755 is fully backward-compatible with all units that used the 8330-3451 or 8330-3452.

Q: Do I need to program or configure the new controller?

A: No. This 9330C755 controller comes pre-configured and ready to use. Simply install it and connect the wires — no programming, dip switches, or calibration required. The controller automatically detects your AC unit configuration (compressor size, fan type, heat option) based on the wiring connections. Just make sure you connect all wires to the correct terminals as documented from your old controller.

Related Products

• Dometic 3311924 Relay Board — Replacement relay board for Dometic Duo Therm RV AC
• RV AC Parts Kit — Safety limit switch and grille for Dometic AC
• 12V 13500BTU Parking AC — Complete rooftop AC heat pump for RVs

Need help repairing your Coleman Mach air conditioner? Contact our technical team with your AC model number and symptoms. Free shipping and duties included.