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wARNINg
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
unit will not run
Condenser fan runs,
compressor doesn't
Insufficient cooling
Compressor short cycles
Registers sweat
high head – low vapor pressures • Restriction in liquid line, expansion device or filter drier • Remove or replace defective component
high head – high or normal vapor • Dirty condenser coil
pressure – Cooling mode
Low head – high vapor pressures • flow check piston size too large
Low vapor – cool compressor –
iced evaporator coil
high vapor pressure
fluctuating head & vapor
pressures
gurgle or pulsing noise at
expansion device or liquid line
24
TROuBLEShOOTINg ChART
pOSSIBLE CAuSE
• power off or loose electrical connection
• Thermostat out of calibration – set too high
• Defective contactor
• Blown fuses
• Transformer defective
• high pressure control open (if provided)
• Interconnecting low voltage wiring damaged
• Run capacitor defective (single phase only)
• Start relay defective (single phase only)
• 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
• flow check piston size too small
• Incorrect capillary tubes
• TxV does not open
• Refrigerant overcharge
• Condenser fan not running
• Air or non-condensibles in system
• Defective Compressor valves
• Incorrect capillary tubes
• Low evaporator airflow
• Operating below 65°f outdoors
• Moisture in system
• TxV limiting refrigerant flow
• Excessive load
• Defective compressor
• TxV hunting
• Air or non-condensate in system
• Air or non-condensibles in system
REMEDy
• 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 450 pSIg
• Replace thermostat wiring
• Replace
• Replace
• 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
• Add start kit components
• 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
• Change to correct size piston
• Change coil assembly
• Replace TxV
• Clean coil
• Correct system charge
• Repair or replace
• Recover refrigerant, evacuate & recharge
• Change to correct size piston
• Replace compressor
• Replace coil assembly
• Increase speed of blower or reduce restriction – replace air
filter
• Add Low Ambient Kit
• Recover refrigerant – evacuate & recharge – add filter drier
• Replace TxV
• Recheck load calculation
• Replace
• Check TxV bulb clamp – check air distribution on coil – replace
TxV
• Recover refrigerant, evacuate & recharge
• Recover refrigerant, evacuate & recharge
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