Carrier 48XL Troubleshooting Chart, SYMPTOM Compressor and outdoor fan will not start, Remedy

SYMPTOM

Compressor and outdoor fan will not start

Compressor will not start but condenser fan runs

Compressor cycles (other than normally sat- isfying) cooling/heating calls

Compressor operates continuously

Excessive head pressure

Head pressure too low

Excessive suction pressure

Suction pressure too low

IFM does not run

IFM operation is intermittent

Table9- Troubleshooting Chart

CAUSE

Power failure

Fuse blown or circuit breaker tripped

Defective contactor, transformer, control relay, or high- pressure, loss-of-charge or low-pressure switch

Insufficient line voltage

Incorrect or faulty wiring

UI setting too low/too high

Units have a 5-minute time delay

Faulty wiring or circuit

Loose connections in compressor Compressor motor burned out, seized, or internal overload open

Defective run capacitor, overload, or PTC (positive temperature coefficient) thermistor

Low input voltage (20 percent low)

Refrigerant overcharge or undercharge

Defective compressor

Insufficient line voltage

Blocked outdoor coil

Defective run/start capacitor, overload or start relay Faulty outdoor fan motor or capacitor

Restriction in refrigerant system

Dirty air filter

Unit undersized for load

UI temperature set too low

Low refrigerant charge

Air in system

Outdoor coil dirty or restricted

Dirty air filter

Dirty indoor or outdoor coil

Refrigerant overcharged

Air in system

Indoor or outdoor air restricted or air short-cycling Low refrigerant charge

Restriction in liquid tube

High heat load

Reversing valve hung up or leaking internally Refrigerant overcharged

Dirty air filter

Low refrigerant charge

Metering device or low side restricted

Insufficient coil airflow

Temperature too low in conditioned area

Outdoor ambient below 55°F (13°C)

Filter drier restricted

Blower wheel not secured to shaft

Insufficient voltage at motor

Power connectors not properly sealed

Water dripping into motor

Connectors not firmly sealed

REMEDY

Call power company

Replace fuse or reset circuit breaker

Replace component

Determine cause and correct

Check wiring diagram and rewire correctly

Reset UI setting

DO NOT bypass this compressor time delay-wait for 5 minutes until time-delay relay is de-energized

Check wiring and repair or replace

Determine cause

Replace compressor

Determine cause and replace

Determine cause and correct

Recover refrigerant, evacuate system, and re- charge to capacities shown on rating plate

Replace and determine cause

Determine cause and correct

Determine cause and correct

Determine cause and replace

Replace

Locate restriction and remove

Replace filter

Decrease load or increase unit size

Reset UI setting

Locate leak, repair, and recharge

Recover refrigerant, evacuate system, and re- charge

Clean coil or remove restriction

Replace filter

Clean coil

Recover excess refrigerant

Recover refrigerant, evacuate system, and re- charge

Determine cause and correct

Check for leaks, repair and recharge Remove restriction

Check for source and eliminate

Replace valve

Recover excess refrigerant

Replace filter

Check for leaks, repair and recharge Remove source of restriction Check filter-replace if necessary Reset UI setting

Verify low-ambient cooling enabled in UI Replace

Properly tighten blower wheel to shaft Determine cause and correct

Connectors should snap easily; do not force Verify proper drip loops in connector wires Gently pull wires individually to be sure they are crimped into the housing

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