Carrier 38QUS012D8S Service Manual page 113

2.4 Resolving Typical Malfunctions
2.4.1 For Indoor Units
2.4.1.1 Temperature Sensor Open or Short Circuit
Malfunction conditions
Possible causes
Check connections
Check connections
between temperature
between temperature
sensor and PCB. Are the
sensor and PCB. Are the
connections in working
connections in working
order?
order?
Yes
Measure the resistance value
Measure the resistance value
of the sensor via Appendix 1
of the sensor via Appendix 1
Is it normal?
Is it normal?
Yes
Replace the indoor PCB
Replace the indoor PCB
2.4.1.2. Outdoor Unit Malfunction
Is the main board
Is the main board
displaying an error?
displaying an error?
Yes
Refer to the prescribed
Refer to the prescribed
steps for resolving the
steps for resolving the
issue
issue
Electrical Control System
If the sampling voltage is lower than 0.06V or higher than 4.94V,
the LED will display the failure.
● Wiring mistakes
● Faulty sensor
● Faulty PCB
No Correct the connections
Correct the connections
No Replace the sensor
Replace the sensor
Power off, then restart the unit 2
Power off, then restart the unit 2
minutes later. Does the outdoor main
minutes later. Does the outdoor main
No
board display an error code a few
board display an error code a few
minutes later?
minutes later?
Yes
Troubleshooting
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