MCQUAY Service Guide Book Diagnosis
71
APJ1 –M5WMY10/15KR
Indoor LED Indication
The operation lamp (green) flashes when any of the following errors is detected.
1. When a protection device of the indoor or outdoor unit is activated or when the thermistor
malfunctions, disabling equipment operation.
2. When a signal transmission error occurs between the indoor and outdoor units.
Diagnosis Step
1. Hold down TIMER CANCEL button for 5 seconds, a “ ” indication flashes on the temperature
display section.
2. Press TIMER CANCEL repeatedly until indoor buzzer produces a long beep. This indicates the error
code, refers to Error Codes table and is displayed on the temperature display section.
3. A short beep or two consecutive beeps indicate non-corresponding error codes.
4. To cancel the error code display, hold down TIMER CANCEL button for 5 seconds. Alternatively, the
code display will cancel itself if the button is not pressed for 1 minute.
Error Codes:
Error
Code
Description
SYSTEM
00 Normal
UA Indoor-Outdoor combination fault
U0 Refrigerant Shortage
U2 Drop voltage or main circuit overvoltage
U4
Failure of transmission (between indoor
and outdoor unit)
INDOOR UNIT
A1 Indoor PCB defectiveness
A5
High pressure control or freeze-up
protector
A6 Fan motor fault
C4
Faulty heat exchanger temperature
sensor
C9 Faulty suction air temperature sensor
OUTDOOR UNIT
EA Cooling-Heating switching error
E1 Circuit board fault
E5 OL started
E6 Faulty compressor start up
Error
Code
Description
OUTDOOR UNIT
E7 DC fan motor fault
E8 Over current input
F3 High temperature discharge pipe control
F6 High pressure control (in cooling)
H0 Sensor fault
H6
Operation fault due to faulty position
detection sensor
H8 DC current sensor fault
H9 Faulty suction air temperature sensor
J3
Faulty discharge pipe temperature
sensor
J6
Faulty heat exchanger temperature
sensor
L3 Electrical Part heat fault
L4
High temperature at Inverter circuit
heat sink
L5 Output over current
P4
Faulty Inverter circuit heat sink
temperature sensor
Timer Cancel
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