Coleman-Mach Slow Flashing Green (1 Time/Sec) fault code — Thermostat
Applies to: Coleman-Mach 9420-330 multi-zone wall thermostat
What Slow Flashing Green (1 Time/Sec) means
The Coleman-Mach 9420-330 guide lists a slow flashing green status LED at 1 time per second as the device having been online but having no valid network message for 5 seconds.
Owner-safe checks
- Record the LED activity only if it is visible without tools.
- Record thermostat model, zone, and whether normal touchscreen controls still respond.
- If the slow flashing LED state persists, stop the affected heating or cooling call from normal controls and contact qualified service.
Service-only work
- Thermostat removal, wiring, zone control box, network communication hardware, installation, and power diagnosis are trained technician work.
Safety boundary
Use normal thermostat controls only. Do not take the thermostat off the wall or disturb thermostat/network hardware unless qualified.
Official sources
Related symptom guides
- Coleman-Mach 9420-330 thermostat status LED pattern
- RV thermostat delay or no response
- Pre-service checklist for RV appliance calls