McQuay MWM Service Manual page 67

MCQUAY Service Guide Book
9. Disconnection of
discharge thermistor 1 / 2
10. Heat Exchanger 1 / 2
high temperature
11. Indoor HEX 1 / 2
abnormal temperature
12. Indoor fan overload
13. Return air sensor short /
open
14. Outdoor air sensor
short / open
15. Comp discharge sensor
1 / 2 short
16. Comp discharge sensor
1 / 2 open
17. Outdoor HEX sensor 1 /
2 short
18. Outdoor HEX sensor 1 /
2 open
19. Indoor HEX sensor 1 / 2
short
20. Indoor HEX sensor 1 / 2
open
There are two LEDs in economizer controller board, which are green LED and red LED. Green LED will
blink when economizer controller board is powered-up. Red LED will blink when error(s) occur. Refer the
table below for error codes and their meaning:-
Note:
All the errors occur in economizer controller board will not affect the normal operation of rooftop unit.
Condenser fan motor faulty
Main PCB faulty
Poor sensor connection
Discharge sensor malfunction /
poor sensor connection
Insufficient Air Flow / Air Short
Circuit
Heat Exchanger Dirty
Condenser fan motor faulty
Compressor malfunction
EXV or EXV PCB faulty
Main PCB faulty
Poor coil sensor connection
Compressor malfunction
Leaking in piping joint
EXV or EXV PCB faulty
Main PCB faulty
Motor internal over current
protection faulty
Winding resistance out of spec
Fan motor short body
Main PCB faulty
Faulty Sensor / Poor sensor
connection
Faulty Sensor / Poor sensor
connection
Faulty Sensor / Poor sensor
connection
Faulty Sensor / Poor sensor
connection
Faulty Sensor / Poor sensor
connection
Faulty Sensor / Poor sensor
connection
Faulty Sensor / Poor sensor
connection
Faulty Sensor / Poor sensor
connection
Replace fan motor.
Replace main PCB.
Connect correctly and operate again.
Connect sensor correctly / replace
sensor.
Ensure no obstacle around the unit.
Ensure no dirt or dust on filter and coil.
Replace new motor
Replace new compressor.
Replace new EXV.
Replace main PCB.
Connect sensor correctly / replace new
sensor.
Replace new compressor.
Fix the leak point / Change coil.
Replace new EXV.
Replace main PCB.
Replace indoor fan motor.
Replace main PCB
Connect sensor correctly / replace
sensor.
Connect sensor correctly / replace
sensor.
Connect sensor correctly / replace
sensor.
Connect sensor correctly / replace
sensor.
Connect sensor correctly / replace
sensor.
Connect sensor correctly / replace
sensor.
Connect sensor correctly / replace
sensor.
Connect sensor correctly / replace
sensor.
66
Diagnosis