C. TROUBLESHOOTING
!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 | POSSIBLE CAUSE |
| REMEDY |
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Unit will not run | • Power off or loose electrical connection | • Check for correct voltage at compressor contactor in control box | |
| • Thermostat out of | • | Reset |
| • Defective contactor | • Check for 24 volts at contactor coil - replace if contacts are | |
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| open |
| • Blown fuses | • | Replace fuses |
| • Transformer defective | • | Check |
| • High pressure control open (if provided) | • | |
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| control opens at 610 PSIG |
| • Interconnecting low voltage wiring damaged. | • | Replace thermostat wiring |
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Condenser fan runs, compressor | • Run or start capacitor defective (single phase only) | • | Replace |
doesn’t | • Start relay defective (single phase only) | • | Replace |
| • Loose connection | • Check for correct voltage at compressor - | |
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| check & 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. |
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| At compressor terminals, voltage must be within 10% of rating |
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| plate volts when unit is operating. |
| • Low voltage condition | • Add start kit components | |
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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, | • Recover refrigerant, evacuate & recharge, add filter drier | |
| • Incorrect voltage | • At compressor terminals, voltage must be within 10% of rating | |
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| plate volts when unit is operating. |
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Compressor short cycles | • Incorrect voltage | • At compressor terminals, voltage must be ±10% of | |
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| nameplate marking when unit is operating. |
| • Defective overload protector | • Replace - check for correct voltage | |
| • Refrigerant undercharge | • | Add refrigerant |
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Registers sweat | • Low evaporator airflow | • Increase speed of blower or reduce restriction - replace air | |
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| filter |
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High | • 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 |
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High | • Dirty condenser coil | • | Clean coil |
pressure - Cooling mode | • Refrigerant overcharge | • | Correct system charge |
| • Outdoor fan not running | • | Repair or replace |
| • Air or | • Recover refrigerant, evacuate & recharge | |
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High | • Low air flow - condenser coil | • Check filters - correct to speed | |
pressure - Heating mode | • Refrigerant overcharge | • | Correct system charge |
| • Air or | • Recover refrigerant, evacuate & recharge | |
| • Dirty condenser coil | • | Check filter - clean coil |
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Low | • Defective Compressor valves | • | Replace compressor |
| • Defective TXV(s) | • | Replace coil assembly |
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Low vapor - cool compressor - | • Low evaporator airflow | • Increase speed of blower or reduce restriction - replace air filter | |
iced evaporator coil | • Operating below 65°F outdoors | • Add Low Ambient Kit | |
| • Moisture in system | • Recover refrigerant - evacuate & recharge - add filter drier | |
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High vapor pressure | • Excessive load | • | Recheck load calculation |
| • Defective compressor | • | Replace |
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Fluctuating head & vapor | • TXV hunting | • Check TXV bulb clamp - check air distribution on coil - replace | |
pressure |
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| TXV |
| • Air or | • Recover refrigerant, evacuate & recharge | |
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Gurgle or pulsing noise at | • Air or | • | Recover refrigerant, evacuate & recharge |
expansion device or liquid line |
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