5103 (U4) — Gas pipe temperature thermistor open/short

What does 5103 (U4) mean?

This code indicates an open or short circuit condition with the gas pipe temperature thermistor (TH23). This thermistor monitors the temperature of the gas pipe in the outdoor unit and is crucial for system operation.

• Disconnection or contact failure of thermistor connectors.
• Characteristic defect of the thermistor.
• Defective outdoor multi controller circuit board.

Click steps to track your progress.

1. 1

   Check the connectors for the gas pipe temperature thermistor (TH23). Make sure they are fully engaged and free from damage.

2. 2

   Verify the integrity and resistance of the thermistor itself using appropriate testing equipment.

3. 3

   Power cycle the outdoor unit by turning it off at the main breaker, waiting 30 seconds, and then turning it back on.

4. 4

   If connections and the thermistor seem fine but the error recurs, the outdoor multi controller circuit board should be professionally inspected.