5102 (U4) — Liquid pipe temperature thermistor or Suction pipe temperature thermistor open/short

What does 5102 (U4) mean?

This code signifies a problem with the liquid pipe temperature thermistor (TH22) or the suction pipe temperature thermistor (TH6) in the outdoor unit. It indicates an open or short circuit in the thermistor's wiring or component, leading to incorrect temperature readings.

• 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

   Examine the connectors for the liquid pipe temperature thermistor (TH22) and suction pipe temperature thermistor (TH6). Confirm they are firmly seated and clean.

2. 2

   Test the thermistor for proper functionality or resistance if you have the tools to do so.

3. 3

   Turn off the power to the outdoor unit at the circuit breaker, wait, and then turn it back on.

4. 4

   If the issue persists after checking connections and power cycling, the outdoor multi controller circuit board might be defective and require professional attention.