Carrier 38MBQ Series - Temperature Sensor Error Diagnosis; Troubleshooting Sensor Faults (E4;E5;F1-F3)

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DIAGNOSIS AND SOLUTION (CONT)
Table 21—Open Circuit or Short Circuit of Temperature Sensor Diagnosis and Solution (E4/E5/F1/F2/F3)
Error Code E4/E5/F1/F2/F3
Malfunction Decision Conditions If the sampling voltage is lower than 0.06V or higher than 4.94V, the LED displays the failure.
Supposed Causes
S Wiring mistake
S Sensor Faulty
Check the connection
between temperature
sensor and PCB. Is it
properly wired?
Ensure proper connectionNo
Yes
Replace indoor or outdoor
main PCB
Measure the resistance
value of the sensor. Is it
within acceptable
parameters?
Replace the sensor
No
Yes
Fig. 20 – Test