Sinclair SCV-750EB Service Manual page 138

5.33 P3 troubleshooting
Digital display output
Description
P3 indicates ambient temperature too high for cooling mode

All units stop running.

Error code is only displayed on main PCB and user interface.

Possible causes
Ambient temperature sensor is interfered by other heat sources and the temperature detection value exceeds 65°C

Ambient temperature sensor damaged
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Main control board damaged

Procedure
Ambient temperature sensor is interfered
by other heat sources
Ambient temperature sensor
Replace main control board
Note:
1. For SCV-750EB and SCV-1400EB, ambient temperature sensor connection port is CN30 on the main PCB (labeled 23 in Part 4, 2.2.1 Main PCB component).
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 Part 4, 6.1 "Temperature Sensor Resistance Characteristics".
2. For SCV-900EB and SCV-1800EB, ambient temperature sensor connection port is CN1 on the main PCB (labeled 29 in Part 4, 2.2.1 Main PCB component).
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 Part 4, 6.1 "Temperature Sensor Resistance Characteristics".
136
P3
No
1 damaged
No
Yes
Eliminate interfering heat source
Yes
Replace Ambient temperature sensor