Outdoor Heat Exchanger Thermistor 3 Failure (Tho-R3)

What does E37-3 mean?

The third outdoor heat exchanger thermistor (Tho-R3) is defective. This prevents accurate temperature measurement of a specific section of the outdoor coil, impacting system control and protection.

1. 1

   Measure the resistance of thermistor Tho-R3 at its leads — compare to a resistance-temperature chart if available.

2. 2

   Inspect the connector for Tho-R3 on the outdoor unit PCB — verify it is securely seated and free from corrosion.