Coleman-Mach ยท 14 codes
Coleman-Mach RV thermostat fault codes
Every fault code, display message, and status light listed in Coleman-Mach's manuals and support pages for Coleman-Mach 9420-330 multi-zone wall thermostat (status LED); Coleman-Mach 9420-381 / 9420-382 digital thermostats; Coleman-Mach 9330-33 multiple-zone thermostat; Coleman-Mach 6535-335 heat pump wall thermostat; Coleman-Mach 6536-335 heat pump wall thermostat; Coleman-Mach 9630-351 / 9630-352 / 9630-353 heat pump thermostats; Coleman-Mach RvComfort / True-Air heat pump thermostats. Select a code for what it means, what you can safely check, and when to call a technician.
Confirm your model
Codes are model-specific. Match the model number on the appliance data label to one of these before using the table:
Coleman-Mach 9420-330 multi-zone wall thermostat, 9420-381, 9420-382, 9330-33 multiple-zone thermostat, Coleman-Mach 6535-335, Coleman-Mach 6536-335, Coleman-Mach 9630-352, Coleman-Mach 9630-351, Coleman-Mach 9630-353, RvComfort.HP, RvComfort.PHP, Coleman True-Air, RvComfort.ZC
Where to look and what to record
- thermostat model
- zone number
- remote sensor location
- rooftop unit model
- indoor temperature
- sun/heat exposure near thermostat
- fuse panel status
- thermostat ID
Code table
| Code | What the manufacturer says | Listed for |
|---|---|---|
| Er | Er displays when ambient temperature is outside the thermostat display range or when a remote temperature sensor has a problem. | Coleman-Mach 9330-33 multiple-zone thermostat |
| HI | HI displays when current temperature is above 99 F (37 C). | Coleman-Mach 9420-381 / 9420-382 digital thermostats |
| LO | LO displays when current temperature is below 33 F (0 C). | Coleman-Mach 9420-381 / 9420-382 digital thermostats |
| ELEC flashing | ELEC flashes when the heat pump is in lockout because electric heat could not satisfy the thermostat call. | Coleman-Mach 9630-351 / 9630-352 / 9630-353 heat pump thermostats |
| DIFF flashing | DIFF flashes on the LCD when 2nd stage heat is operating because the heat pump cannot satisfy the thermostat. | Coleman-Mach 6535-335 heat pump wall thermostat |
| DIFF | DIFF displays when backup heat is operating and the heat pump is locked out. / Coleman-Mach's heat pump thermostat guide says DIFF can show during the two hour lockout after three heat-pump strikes, with electric heat unavailable during that lockout. | Coleman-Mach 6536-335 heat pump wall thermostat; Coleman-Mach RvComfort / True-Air heat pump thermostats |
| FLASHING GAS HEAT | Coleman-Mach's heat pump thermostat guide says FLASHING GAS HEAT can show during the two hour lockout after three heat-pump strikes, with electric heat unavailable during that lockout. | Coleman-Mach RvComfort / True-Air heat pump thermostats |
| Solid Green | The device being connected to the network and communicating properly | Coleman-Mach 9420-330 multi-zone wall thermostat (status LED) |
| Off | The device having no power or having completely failed | Coleman-Mach 9420-330 multi-zone wall thermostat (status LED) |
| Solid Red | The device being offline and not connected to the network | Coleman-Mach 9420-330 multi-zone wall thermostat (status LED) |
| Fast Flashing Green (4 Times/Sec) | The device attempting to make its initial network connection | Coleman-Mach 9420-330 multi-zone wall thermostat (status LED) |
| Slow Flashing Green (1 Time/Sec) | The device having been online but having no valid network message for 5 seconds | Coleman-Mach 9420-330 multi-zone wall thermostat (status LED) |
| Alternating Red & Orange | The device being offline and attempting to reconnect within 30 seconds | Coleman-Mach 9420-330 multi-zone wall thermostat (status LED) |
| Alternating Green & Orange | The device being currently online but having gone offline 2 or more times | Coleman-Mach 9420-330 multi-zone wall thermostat (status LED) |
Disconnect power before thermostat or HVAC service. Do not open rooftop electrical compartments unless qualified.
Disconnect power before thermostat or HVAC service. Do not probe control wiring unless qualified.
Use normal thermostat controls only. Stop electric heat attempts and call Coleman-Mach/Airxcel or qualified RV HVAC service if lockout repeats, the coach cannot be kept warm, or there are electrical symptoms.
Troubleshooting guides
- Coleman-Mach thermostat heat-pump lockout display
- Coleman-Mach thermostat fan only or no cooling call
- Coleman-Mach thermostat shows GAS or flashing Elec assist
- Coleman-Mach 9420-330 thermostat status LED pattern
- Coleman-Mach 48000 heat pump high-pressure switch lockout
- Coleman-Mach Wi-Fi thermostat compatibility before upgrade
- Coleman-Mach Wi-Fi thermostat Eco, Comfort, or schedule mode surprise
- Coleman-Mach Wi-Fi thermostat will not connect to the app
- RV thermostat display shows LO, HI, or sensor code
- RV thermostat communication error