Daikin FTXB50BV1B Service Manual page 43

Service Diagnosis
Description
4 WAY VALVE ABNORMALITY
Supposed Cause
1. Thermistor defective.
2. 4 way valve defective.
3. Outdoor PCB defective.
4. Insuffi cient gas.
5. Foreign substance mixed in refrigerant.
6. Stop valve defective.
7. Disconnect of 4 way valve coil.
Troubleshooting
*Remark:
Refer to Appendix A for thermistor resistance checking procedures.(Page 59, item 6.1)
Refer to Appendix A for Four way valve performance checking procedures.(Page 61 ,item 6.2)
Refer to Appendix A for Inverter unit refrigerant check procedures.(Page 62 ,item 6.4)
37
Four way valve
coil disconnected
(loose)?
No
Harness
disconnected?
No
Check the continuity of the four
way valve coil and harness.
Disconnect the harness from
the connector.
Resistance
between harnesses.
within spec?
Yes
Check the four way
valve switching
output.
Functioning
Any thermistor
disconnected?
No
Check the thermistors.
Functioning
Check the
refrigerant
line.
Functioning
EA
Yes
Yes
No
Malfunction
Yes
Malfunction
Malfunction
Correct the four way valve
coil.
Reconnect the harness.
Replace the four way valve
coil.
Replace the outdoor unit PCB.
Reconnect the thermistor(s).
Replace the defective
thermistor(s).
Refer to the refrigerant
line check procedure.
Replace the four way valve
(defective or dust-clogged).