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9.0 DIAGNOSTICS & TROUBLESHOOTING
9.8 General Troubleshooting Guide
WARNING:
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Diagnostics
SYMPTOM
POSSIBLE CAUSE
REMEDY
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high
• Defective control board
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• Transformer defective
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condensing unit.
• Reset.
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Outdoor fan runs,
compressor doesn't
• Run or start capacitor defective
• Start relay defective
• Loose connection
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• Replace.
• Replace.
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tighten all connections.
• Wait at least 3 hours for overload to reset. If still open,
replace the compressor.
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• Improperly sized unit
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• Incorrect refrigerant charge
• Air, noncondensibles, or moisture in system
• Restricted refrigerant circuit
• Recalculate load.
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ton.
• Charge per procedure attached to unit service panel.
• Recover refrigerant. Evacuate and recharge. Add or
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• Locate restriction and clear.
Compressor short
cycles
• Incorrect voltage
• Defective overload protector
• Refrigerant undercharge or overcharge
• (HPS or LPC cycling)
• At compressor terminals, voltage must be ± 10% of
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• Adjust charge per charging chart.
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pressures
• Restriction in liquid line, expansion device, or
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• Remove or replace defective component.
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High head, high
or normal vapor
pressure – Cooling
mode
• Dirty outdoor coil
• Refrigerant overcharge
• Outdoor fan not running
• Air or noncondensibles in system
• Clean coil.
• Correct system charge.
• Repair or replace.
• Recover refrigerant. Evacuate and recharge.
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pressures
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• Bad compressor
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• Replace compressor.
• Replace reversing valve.
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iced indoor coil
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• Moisture in system
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drier.
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High vapor pressure
• Excessive load
• Defective compressor
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• Replace.
Fluctuating head and
vapor pressures
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• Air or noncondensibles in system
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• Recover refrigerant. Evacuate and recharge.
Gurgle or pulsing
noise at expansion
device or liquid line
• Air or noncondensibles in system
• Undercharged system
• Recover refrigerant. Evacuate and recharge.
• Adjust charge per charging chart.