McQuay MCK Service Guide Book

58
By means of diagnostic flow chart:
Generally, there are two kinds of problems, i.e. starting failure and insufficient
cooling/heating. “Starting failure” is caused by electrical defect while improper application
or defects in refrigerant circuit causes “Insufficient cooling / heating”.
i ) Diagnosis of Electric circuit
Faulty
Faulty
: Faulty : Check : Cause : Remedy
No cooling/heating ( Unit fails to start )
Evaporator
fan motor
No voltage or low voltage
Unit power
supply
Wrong phase/missing
phase
Get the right voltage
Repair the power line
Tripped
Tripped
Blown
Running
Fuse for
operation
circuit
Components shorted
Connections loose
Repair or replace
the components
Tighten the connections
Over current
relay for
evaporator
fan
High or low voltage
Wrong phase/missing
phase
Stop
Get the right voltage
Check the power
supply to the motor:
repair when necessary
Check the power
supply to the motor:
repair when necessary
Evaporator
fan contactor
Coil burned
Contact faulty
Faulty fan motor
Defective operation
Change the contactor
Repair or change
the motor
Repair the contacts
Repair or change
the switch
Condenser
fan motor
Over current
relay for
condenser
fan
No voltage or low voltage
Wrong phase/missing
phase
Get the right voltage
Running
Stop
1
2

McQuay MCK Specifications

General

Brand	McQuay
Model	MCK
Category	Air Conditioner
Language	English