XII. TROUBLESHOOTING
WARNING
DISCONNECT ALL POWER TO UNIT BEFORE SERVICING. CONTACTOR MAY BREAK ONLY ONE SIDE. FAIL-
URE TO SHUT OFF POWER CAN CAUSE ELECTRICAL SHOCK RESULTING IN PERSONAL INJURY OR DEATH.
SYMPTOM
Unit will not run
Condenser fan runs, compressor
doesn't
Insufficient cooling
Compressor short cycles
Registers sweat
High head pressure-
low vapor pressures
High head pressure-high or
normal vapor pressure -
Cooling mode
Low head pressure-high vapor
pressures
Low vapor pressure -
cool compressor -
iced evaporator coil
High vapor pressure
Fluctuating head & vapor
pressures
Gurgle or pulsing noise at
expansion device or liquid line
COOLING TROUBLE SHOOTING CHART
POSSIBLE CAUSE
• Power off or loose electrical connection
• Thermostat out of calibration-set too high
• Failed contactor
• Blown fuses
• Transformer defective
• High pressure control open (if provided)
• Interconnecting low voltage wiring damaged
• Loose connection
• Compressor stuck, grounded or open motor winding
open internal overload.
• Low voltage condition
• Low voltage condition
• Improperly sized unit
• Improper airflow
• Incorrect refrigerant charge
• Air, non-condensibles or moisture in system
• Incorrect voltage
• Incorrect voltage
• Defective overload protector
• Refrigerant undercharge
• Low evaporator airflow
• Restriction in liquid line, expansion device or filter drier
• TXV does not open
• Dirty condenser coil
• Refrigerant overcharge
• Condenser fan not running
• Air or non-condensibles in system
• Defective Compressor valves
• Low evaporator airflow
• Operating below 65°F outdoors
• Moisture in system
• Excessive load
• Defective compressor
• TXV hunting
• Air or non-condensibles in system
• Air or non-condensibles in system
FIGURE 20
•
Check for correct voltage at compressor contactor in control
box
•
Reset
•
Check for 24 volts at contactor coil - replace if contacts are
open
•
Replace fuses
•
Check wiring-replace transformer
•
Reset-also see high head pressure remedy-The high pressure
control opens at 610 PSIG
•
Replace thermostat wiring
•
Check for correct voltage at compressor -
check & tighten all connections
•
Wait at least 2 hours for overload to reset.
If still open, replace the compressor.
•
At compressor terminals, voltage must be within 10% of rating
plate volts when unit is operating.
•
Increase voltage
•
Recalculate load
•
Check - should be approximately 400 CFM per ton.
•
Charge per procedure attached to unit service panel.
•
Recover refrigerant, evacuate & recharge, add filter drier
•
At compressor terminals, voltage must be within 10% of rating
plate volts when unit is operating.
•
At compressor terminals, voltage must be ± 10% of
nameplate marking when unit is operating.
•
Replace - check for correct voltage
•
Add refrigerant
•
Increase speed of blower or reduce restriction - replace air
filter
•
Remove or replace defective component
•
Replace TXV
•
Clean coil
•
Correct system charge
•
Repair or replace
•
Recover refrigerant, evacuate & recharge
•
Replace compressor
•
Increase speed of blower or reduce restriction - replace air
filter
•
Add Low Ambient Kit
•
Recover refrigerant - evacuate & recharge - add filter drier
•
Recheck load calculation
•
Replace
•
Check TXV bulb clamp - check air distribution on coil - replace
TXV
•
Recover refrigerant, evacuate & recharge
•
Recover refrigerant, evacuate & recharge
REMEDY
43