Coleman-Mach thermostat heat-pump lockout display
Use this when a Coleman-Mach heat-pump thermostat shows ELEC flashing, DIFF, DIFF flashing, or FLASHING GAS HEAT after repeated unmet electric-heat calls.
Owner-safe checklist
- Record thermostat family, zone, display text, heat mode, room temperature, set point, outside temperature estimate, and how long the lockout has been active.
- Wait through the manual-described lockout period if the RV remains safe and warm enough.
- After lockout clears, keep the electric-heat set point within four degrees of room temperature before trying electric heat again.
- Use normal backup heat controls during the lockout if available, and contact qualified service if lockout repeats in moderate outdoor conditions.
Official sources
- Coleman-Mach 9630-352 Heat Pump Installation, Operation & Application Guide
- Coleman-Mach 9630-351 and 9630-353 Heat Pump Installation, Operation & Application Guide
- Coleman-Mach 6535-335 2 Stage Heat Pump Wall Thermostat Installation and Operating Instructions
- Coleman-Mach 6536-335 2 Stage Heat Pump Wall Thermostat Installation and Operating Instructions
- Coleman-Mach Heat Pump Thermostat Function Guide