ClimateMaster ACL2120CAZ, Installation Instructions Manual, Page: 40 / 52

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9.0 DIAGNOSTICS & TROUBLESHOOTING
9.2 General Troubleshooting Guide
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
Unit will not run • Power off or loose electrical connection
• Thermostat out of calibration – set too low or
high
• Blown fuses/tripped breaker
• Transformer defective
• High-pressure control open
• Low pressure control open
• Miswiring of thermostat
• Check for correct voltage at line voltage connections in
condensing unit.
• Adjust thermostat.
• Replace fuses/reset breaker.
• Check wiring. Replace transformer.
• See high head pressure remedy.
• See low suction pressure remedy.
• Check thermostat wiring.
Outdoor fan runs,
compressor doesn't
• Loose connection
• Compressor stuck, grounded or open motor
winding, open internal overload.
• Check for correct voltage at compressor. Check and
tighten all connections.
• Wait at least 3 hours for overload to reset. If still open,
replace the compressor.
Insufficient cooling • Improperly sized unit
• Improper indoor airflow
• Incorrect refrigerant charge
• Air, noncondensibles, or moisture in system
• Restricted refrigerant circuit
• Recalculate building load.
• Check. Should be approximately 350-400 CFM [165-
189 L/s] per ton.
• Charge per procedure attached to unit service panel.
• Recover refrigerant. Evacuate and recharge.
• Locate restriction and clear. Add or replace filter drier.
Compressor short
cycles
• Incorrect voltage
• Defective overload protector
• Refrigerant undercharge or overcharge (HPC or
LPC cycling)
• At compressor terminals, voltage must be ± 10% of
nameplate marking when unit is operating.
• Replace compressor. Check for correct voltage.
• Adjust charge per charging chart.
Registers sweat • Low indoor airflow • Increase speed of blower or reduce restriction.
Replace air filter.
High head, low
suction pressures
• Restriction in liquid line, expansion device, or
filter drier
• Bad TXV
• Remove or replace defective component.
• Replace TXV.
High head, high
or normal suction
pressure
• 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.
Low head, high vapor
pressures
• Bad TXV
• Bad compressor
• Replace TXV.
• Replace compressor.
Low suction
pressure, iced indoor
coil
• Low indoor airflow
• Operating below 65°F [18°C] outdoors
• Moisture in system
• Low refrigerant charge
• Increase speed of blower or reduce restriction.
Replace air filter.
• Add Low Ambient Kit.
• Recover refrigerant. Evacuate and recharge. Add filter
drier.
• Check refrigerant charge and check for leaks.
High suction pressure • Excessive load
• Defective compressor
• Recheck load calculation.
• Replace.
Fluctuating head and
suction pressures
• TXV hunting
• Air or noncondensibles in system • Check TXV bulb clamp. Check air distribution on coil.
Replace TXV.
• 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.
Diagnostics