5107 (1221) Temperature sensor fault - Outside temperature (TH7)

What does 5107 (1221) mean?

This fault indicates a problem with the outdoor temperature sensor (TH7). The sensor could be short-circuited or open, providing incorrect environmental temperature data to the system.

• Pinched or damaged lead wire for the TH7 thermistor.
• Loose or disconnected connector for TH7.
• Short detection (TH7 reading 110°C [230°F] or above).
• Open detection (TH7 reading -40°C [-40°F] or below).
• Control board malfunction if sensor readings are far from actual temperature.

Click steps to track your progress.

1. 1

   Turn off the power to the unit at the circuit breaker.

2. 2

   Visually inspect the wiring for the TH7 temperature sensor for any signs of pinching, damage, or wear on the wire coating.

3. 3

   Ensure the TH7 sensor connector is securely attached.

4. 4

   If you have an LED monitor, check the intake temperature of the sensor; if it's far from the actual temperature, note this.

5. 5

   Restore power. If the problem recurs, contact a service professional to check the thermistor resistance and potentially replace the control board.