Daikin IM 972-1 49
Troubleshooting
Troubleshooting
Cooling Troubleshooting Chart
DANGER
Disconnect all power to unit before servicing. Contactor may break only one side. Failure to shut off power can cause electrical
shock resulting in personal injury or death.
SYMPTOM POSSIBLE CAUSE REMEDY
Unit will not run Power off or loose electrical connection
Check for correct voltage at compressor
contactor in control box
Thermostat out of calibration-set too high Reset
Failed contactor
Check for 24 volts at contactor coil replace if
contacts are open
Blown fuses Replace fuses
Transformer defective Check wiring-replace transformer
High pressure control open (if provided)
Reset-also see high head pressure remedy-The
high pressure control opens at 450 PSIG
Interconnecting low voltage wiring damaged Replace thermostat wiring
Condenser fan runs, compressor doesn’t Loose connection
Check for correct voltage at compressor check
& tighten all connections
Compressor stuck, grounded or open motor
winding, open internal overload.
Wait at least 2 hours for overload to reset. If still
open, replace the compressor.
Low voltage condition
At compressor terminals, voltage must be within
10% of rating plate volts when unit is operating
Low voltage condition Add start kit components
Insufficient cooling Improperly sized unit Recalculate load
Improper airflow
Check should be approximately 400 CFM per
ton.
Incorrect refrigerant charge
Charge per procedure attached to unit service
panel
Air, non-condensable or moisture in system
Recover refrigerant, evacuate & recharge, add
filter drier
Incorrect voltage
At compressor terminals, voltage must be within
10% of rating plate volts when unit is operating.
Compressor short cycles Incorrect voltage
At compressor terminals, voltage must be ±10%
of nameplate marking when unit is operating.
Defective overload protector Replace check for correct voltage
Refrigerant undercharge Add refrigerant
Registers sweat Low evaporator airflow
Increase speed of blower or reduce restriction
replace air filter
High head-low vapor pressures
Restriction in liquid line, expansion device or filter
drier
Remove or replace defective component
Flow check piston size too small Change to correct size piston
Incorrect capillary tubes Change coil assembly
High head-high or normal vapor pressure
Cooling mode
Dirty condenser coil Clean coil
Refrigerant overcharge Correct system charge
Condenser fan not running Repair or replace
Air or non-condensable in system Recover refrigerant, evacuate & recharge
Low vapor - cool compressor iced
evaporator coil
Defective Compressor valves Replace compressor
Incorrect capillary tubes Replace coil assembly
Low vapor cool evaporator coil Low evaporator airflow
Increase speed of blower or reduce restriction
replace air filter
Operating below 65°F outdoors Add Low Ambient Kit
Moisture in system
Recover refrigerant evacuate & recharge add
filter drier
High vapor pressure Excessive load Recheck load calculation
Defective compressor Replace
Fluctuating head & vapor Air or non-condensate in system Recover refrigerant, evacuate & recharge
Gurgle or pulsing noise at expansion
device or liquid line
Air or non-condensable in system Recover refrigerant, evacuate & recharge
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