Heater displays E07 and will not run the compressor

Safety first: Disconnect power before working inside the unit.

• Locate ambient sensor: Find the air temperature sensor near the evaporator coil or air intake grille. It is usually a small probe on a bracket.
• Inspect sensor and wiring: Check for physical damage, pinched wires, or rodent chewing. Repair or replace damaged wiring.
• Check connector: Unplug the sensor from the harness and from the control board, inspect for corrosion, clean, and reconnect firmly.
• Secure sensor position: Ensure the sensor is positioned in free airflow, not touching hot components or metal surfaces that could distort readings.
• Restart heater: Restore power and attempt to start the heater to see if E07 clears.

If E07 remains, the ambient sensor is likely defective and should be replaced with a BWT-compatible NTC sensor. If replacement does not help, the control board sensor input may be faulty.