Fujitsu AOUH18LMAS1, Service Manual

Page: 77 / 215

2-20. E: 73.X. Heat exchanger (Middle/Outlet) temperature
thermistor error (Outdoor unit)
Indicator
Indoor unit
Operation indicator 7 time flash
Timer indicator 3 time flash
Economy indicator Continuous flash
Error code E: 73
outdoor unit Refer to "Error code table (Outdoor unit)" on page 03-4
Detective actuator
Heat exchanger liquid temperature
thermistor
• Heat exchanger liquid temperature thermistor short
or open detected
• Heat exchanger middle temperature thermistor
short or open detected
Heat exchanger middle
temperature thermistor
Forecast of cause
Connector failure
Thermistor failure
Main PCB failure
Check Point 1 : Check the connector connection and cable open
• Connector connection state check
• Cable open check
Check Point 2 : Check the thermistor
• For the outdoor unit heat exchanger thermistor resistance value, refer to "Ther-
mistor resistance values" on page 03-88.
• If thermistor is either open or shorted, replace it and reset the power.
Check point 3. Check voltage of main PCB
Make sure circuit diagram of outdoor unit and check terminal voltage at thermistor
(DC 5.0 V).
NOTE: For details of thermistor connector, refer to "→iring diagrams" in Chapter 2.
TECHNICAL DATA AND PARTS LIST on page 02-18.
If the voltage does not appear, replace main PCB.
End
2-20. E: 73.↓. Heat exchanger (Middle/Outlet) temperature thermistor error (Outdoor
unit)
- (03-35) -
2. Troubleshooting with error code
TR
O
U
B
LESH
O
O
TI
N
G
TR
O
U
B
LESH
O
O
TI
N
G