SYMPTOM POSSIBLE CAUSE REMEDY
U
nit 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
• Defective contactor • Check for 24 volts at contactor coil - replace if contacts are
o
pen
•
Blown fuses • Replace fuses
•
Transformer defective • Check wiring-replace transformer
• High pressure control open (if provided) • Reset-also see high head pressure remedy-
• Interconnecting low voltage wiring damaged • Replace thermostat wiring
Condenser fan runs, compressor • Run capacitor defective (single phase only) • Replace
d
oesn’t • Loose connection • Check for correct voltage at compressor -
c
heck & tighten all connections
•
Compressor stuck, grounded or open motor winding, • Wait at least 2 hours for overload to reset.
open internal overload. If still open, replace the compressor.
• Low voltage condition At compressor terminals, voltage must be within 10% of rating
• Low voltage condition • Add start kit components
I
nsufficient 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-condensibles 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
• TXV does not open • Replace TXV
High head-high or normal vapor • Dirty condenser coil • Clean coil
pressure - Cooling mode • Refrigerant overcharge • Correct system charge
• Condenser fan not running • Repair or replace
• Air or non-condensibles in system • Recover refrigerant, evacuate & recharge
High head-high or normal vapor • Low air flow - condenser coil • Check filters - correct to speed
pressure - Heating mode • Refrigerant overcharge • Correct system charge
• Air or non-condensibles in system • Recover refrigerant, evacuate & recharge
• Dirty condenser coil • Check filter - clean coil
Low head-high vapor pressures • Defective Compressor valves • Replace compressor
Low vapor - cool compressor - • Low evaporator airflow • Increase speed of blower or reduce restriction - replace air
iced evaporator coil filter
• Operating below 65°F outdoors • Add Low Ambient Kit
• Moisture in system • Recover refrigerant - evacuate & recharge - add filter drier
• TXV limiting refrigerant flow • Replace TXV
High vapor pressure • Excessive load • Recheck load calculation
• Defective compressor • Replace
Fluctuating head & vapor • TXV hunting • Check TXV bulb clamp - check air distribution on coil - replace
pressures TXV
• Air or non-condensate in system • Recover refrigerant, evacuate & recharge
Gurgle or pulsing noise at • Air or non-condensibles in system • Recover refrigerant, evacuate & recharge
expansion device or liquid line
TROUBLE SHOOTING CHART
D
ISCONNECT 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.
WARNING
!
SEE DEMAND DEFROST CONTROL SECTION FOR DEFROST BOARD FLASH CODES (6 TON UNIT ONLY).
83
To Next Page
Loading...
Need help?
General
