Coleman RV rooftop air conditioner control shows F1 and the unit will not respond to thermostat commands.

Safety: Disconnect 120V shore power and turn OFF the RV’s breaker feeding the Coleman rooftop unit before opening the ceiling assembly.

• Access ceiling plenum: Remove the interior shroud of the Coleman RV air conditioner to expose the control box and wiring.
• Locate the temp sensor: The sensor is typically a small probe or thermistor mounted in the return-air stream or in the control box with two small wires leading to the board.
• Check connections: Reseat the sensor connector on the Coleman-Mach control board. Look for corrosion or moisture; dry and clean as needed.
• Inspect harness: Follow the sensor wires for any pinched or cut sections caused by the shroud or mounting screws. Repair or replace as necessary.
• Replace sensor: If F1 persists, replace the interior temp sensor with a Coleman-Mach compatible sensor kit.
• Reset system: Restore power, then reset the RV thermostat per its manual (often by holding specific buttons). Verify F1 clears and cooling resumes.

Note: Avoid pulling on sensor wires; always handle by the connector.