Coleman-Mach Air Conditioner: “Wireless comms error”
warning RV air conditioner error codes
What it means
On older Coleman-Mach wireless thermostat systems, the green system LED on the ceiling/main control box flashing twice indicates a communications error: the main control box is not communicating with the wireless thermostat/receiver, so it cannot control the AC or gas furnace.
Most likely causes
- Supply voltage dropped below the required level and the control board locked out (low 12 VDC or 120 VAC) most likely
- Lost link between the main box and the wireless receiver/thermostat common
- 12 V radio-frequency interference inside the RV (antenna boosters, fluorescent ballasts, inverter/charger) disrupting the link less common
- Failed receiver or main board (parts long discontinued) less common
Safe checks you can do yourself
- Check battery state of charge and shore/generator power; confirm both 12 VDC and 120 VAC are healthy and not sagging.
- Confirm the AC breaker and the 12 V fuse for the AC/thermostat circuit are good.
- Reduce potential RF interference sources near the unit if the error is intermittent.
- Note that this wireless remote/receiver system was discontinued and parts are scarce; a manual wall thermostat conversion may be the practical fix.
How to reset / clear Wireless comms error
- Fully reset the board by removing BOTH 120 VAC and 12 VDC power to the unit at the same time, wait, then restore power. Turning off only one source is often not enough.
- Re-establish power and verify the green LED returns to normal (steady) operation.
When to call a technician
The communications error returns after a full dual-power reset, or the wireless receiver/main board is suspected failed, since these legacy parts are discontinued and may require conversion to a wired thermostat.
Applies to
Coleman-Mach wireless thermostat / IR receiver systems (legacy) · ceiling-mounted main control box units
FAQ
What does Coleman-Mach Air Conditioner code "Wireless comms error" mean?
On older Coleman-Mach wireless thermostat systems, the green system LED on the ceiling/main control box flashing twice indicates a communications error: the main control box is not communicating with the wireless thermostat/receiver, so it cannot control the AC or gas furnace.
How do I reset Coleman-Mach Air Conditioner Wireless comms error?
Fully reset the board by removing BOTH 120 VAC and 12 VDC power to the unit at the same time, wait, then restore power. Turning off only one source is often not enough. Re-establish power and verify the green LED returns to normal (steady) operation.
What is the most common cause of Wireless comms error on a Coleman-Mach Air Conditioner?
The most likely cause is supply voltage dropped below the required level and the control board locked out (low 12 vdc or 120 vac).
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Sources
- Coleman Mach AC communications error help — Member discussion describing green LED flashing twice = main box not communicating with receiver (Good Sam Community (RV owner forum))
Note: Source is a reputable RV owner community thread, not a Coleman-Mach manual; the exact two-flash LED meaning and the dual-power reset are owner-reported. Applies to legacy wireless systems, not the current wired digital wall thermostat. Treat as guidance and confirm against the specific unit's documentation.
● Last verified 2026-06-29 · compiled from manufacturer documentation. Codes can vary by model year — always cross-check your unit’s manual.