Coleman-Mach RV air conditioner fault codes
RV roof air conditioners and their thermostats show codes for communication faults, sensor failures, or freeze protection.
How to read the code
Codes usually appear on the wall thermostat. Note whether the code clears when you cycle power, which often points to a communication issue.
All documented codes
E1 warning
The single-zone LCD thermostat has lost its communication link with the rooftop unit's con… E2 warning
The indoor (room) temperature sensor reads as an open circuit or its value is outside the … E3 warning
The indoor (room) temperature sensor is reading as shorted. As with E2, the thermostat can… E4 warning
The outdoor temperature sensor (fitted on heat-pump-equipped models) is open or reading ou… E5 warning
The evaporator freeze sensor is open or reading out of range. Because the thermostat can n… Er warning
On the Coleman-Mach multi-zone LCD thermostat, 'Er' appears in the temperature area of the… Heat-pump strike condition info
In electric-heat (heat-pump) mode the thermostat flashes the 'Elec' segment while it bring… HI info
The thermostat senses a temperature above the top of its measurable range. On the digital … LO info
The thermostat is showing the room temperature it senses is below the bottom of its measur… PTC fuse open (no power) warning
The digital wall thermostat contains a self-resetting PTC (resettable) fuse on its 12 VDC … Short-cycle / compressor delay info
On the digital wall thermostat, the HVAC state segment blinks to show a built-in short-cyc… Wireless comms error warning
On older Coleman-Mach wireless thermostat systems, the green system LED on the ceiling/mai…
The single-zone LCD thermostat has lost its communication link with the rooftop unit's con… E2 warning
The indoor (room) temperature sensor reads as an open circuit or its value is outside the … E3 warning
The indoor (room) temperature sensor is reading as shorted. As with E2, the thermostat can… E4 warning
The outdoor temperature sensor (fitted on heat-pump-equipped models) is open or reading ou… E5 warning
The evaporator freeze sensor is open or reading out of range. Because the thermostat can n… Er warning
On the Coleman-Mach multi-zone LCD thermostat, 'Er' appears in the temperature area of the… Heat-pump strike condition info
In electric-heat (heat-pump) mode the thermostat flashes the 'Elec' segment while it bring… HI info
The thermostat senses a temperature above the top of its measurable range. On the digital … LO info
The thermostat is showing the room temperature it senses is below the bottom of its measur… PTC fuse open (no power) warning
The digital wall thermostat contains a self-resetting PTC (resettable) fuse on its 12 VDC … Short-cycle / compressor delay info
On the digital wall thermostat, the HVAC state segment blinks to show a built-in short-cyc… Wireless comms error warning
On older Coleman-Mach wireless thermostat systems, the green system LED on the ceiling/mai…
Which of these codes apply to your model?
Not every code below exists on every Coleman-Mach air conditioner. Pick your model number to see only the table that applies to it — and which codes it will never show.