Carrier 48DU Installation Instructions Manual page 33

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
Table 10—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
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
33
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