Trane TVR Pro CO Series Service Manual page 67

Procedure
Temperature sensor connection on main
Temperature sensor has short-circuited
Replace outdoor main PCB
Notes:
1. Compressor top temperature sensor and discharge pipe temperature sensor connections are ports CN4 and CN5 on the main PCB (labeled 3 and 4,
respectively, 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 6-3.2 in Part 6, 3.1 "Temperature Sensor Resistance Characteristics".
E7
PCB is loose 1
No
or failed
2
No
Yes
Ensure the sensor is connected properly
Yes
Replace the sensor
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