Room Sensor: this code means that the circuit board is not receiving a signal from the sensing bulb mounted in front of the evaporator coil.
Diagnosis: visually inspect and/or use an ohmmeter to check the following:
- Sensor has come unplugged from the PC board. OR
- Sensor has failed and must be replaced. OR.
- Sensor wire has shorted or opened necessitating the repair of the wire.