Trane 4TVH0086FE000AA Service Manual page 79

Procedure
Temperature sensor connection on main
Temperature sensor has short-circuited
Replace outdoor main PCB
Notes:
1. Outdoor ambient temperature sensor (T4) and heat exchanger temperature sensor (T3) connection is port CN1 on the main PCB (labeled 11 in Figure 5-2.1
in Part 5, 2.1 "Ports").
2. Measure sensor resistance. If the resistance is too low, the sensor has short-circuited. If the resistance is not consistent with the sensor's resistance
characteristics table, the sensor has failed. Refer to Table 6-3.1 in Part 6, 3.1 "Temperature Sensor Resistance Characteristics".
E4
PCB is loose 1
No
or failed
2
No
Yes
Ensure the sensor is connected properly
Yes
Replace the sensor
78