McQuay MDB075B Manual page 103

The following charts are efficient checking procedures for troubleshooting when these fan-coil units are
combined with condensing units with the unit standard wiring. For dual circuited models, perform the
procedures for each.
No Cooling
: Faulty
No Cooling ( Compresor Does Not Start )
Evaporator
Fan Motor
Unit Power
Running
Overcurrent
Evaporator Fan
Evaporator Fan
Condenser
Fan Motor
Overcurrent
Condenser Fan
Running
Condenser Fan
Compressor
Stop
Faulty
Supply
Fuse For
Blown
Operation
Circuit
Tripped
Relay For
Faulty
Contactor
Stop
Tripped
Relay For
Faulty
Contactor
Faulty
Contactor
: Check
No Voltage or Low Voltage
Single-Phase
Components Shorted
Connections Loose
High Voltage or Low Voltage
Single-Phase
Coil Burnt
Contact Faulty
Faulty Fan Motor
Defective Operation Switch
High Voltage or Low Voltage
Single-Phase
Coil Burnt
Contact Faulty
Fan Motor Faulty
Other Electrical Component
Faulty
Coil Burnt
Contact Faulty
Open Compressor Windings
Incorrect Wiring
102
: Cause
Repair or Replace The
Tighten The Connections
Get The Right Voltage
Check The Power Supply To The
Motor : Repair When Necessary
Change The Contactor
Repair Or Change The
Repair Or Replace The Switch
Get The Right Voltage
Check The Power Supply To The
Motor : Repair Connections When
Change The Contactor
Repair or Change The Motor
Change The Contactor
Change The Compressor
Remedy
Get the Right Voltage
Repair the Power
Line
Components
Repair The Contacts
Motor
Necessary
Change The Contacts
Repair or Change If
Necessary
Repair The Contacts
Correct The Wiring