Carrier 50VL---A - Manual (Page 28)

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Table 10 – Troubleshooting Chart
SYMPTOM CAUSE REMEDY
Compressor and outdoor fan will not start
Power failure Call power company
Fuse blown or circuit breaker tripped Replace fuse or reset circuit breaker
Defective contactor, transformer, control relay, or high--
pressure, loss--of--charge or low--pressure switch
Replace component
Insufficient line voltage Determine cause and correct
Incorrect or faulty wiring Check wiring diagram and rewire correctly
Thermostat setting too low/too high Reset thermostat setting
Compressor will not start but condenser fan
runs
Faulty wiring or circuit
Loose connections in compressor
Check wiring and repair or replace
Compressor motor burned out, seized, or Determine cause
internal overload open Replace compressor
Defective run capacitor, overload, or PTC (positive
temperature coefficient) thermistor
Determine cause and replace
One leg of 3--phase power dead
Replace fuse or reset circuit breaker
Determine cause
Low input voltage Determine cause and correct
Three--phase scroll compressor (size 30--
Scroll compressor is rotating in the wrong direction
Correct the direction of rotation by reversing the
60 unit) has a low pressure differential 3--phase power leads to the unit
Compressor cycles (other than normally
satisfying) cooling/heating calls
Refrigerant overcharge or undercharge
Recover refrigerant, evacuate system, and re-
charge to capacities shown on rating plate
Defective compressor Replace and determine cause
Insufficient line voltage Determine cause and correct
Blocked outdoor coil Determine cause and correct
Defective run/start capacitor, overload or start relay Determine cause and replace
Faulty outdoor fan motor or capacitor Replace
Restriction in refrigerant system Locate restriction and remove
Compressor operates continuously
Dirty air filter Replace filter
Unit undersized for load Decrease load or increase unit size
Thermostat temperature set too low Reset thermostat setting
Low refrigerant charge Locate leak, repair, and recharge
Air in system
Recover refrigerant, evacuate system, and re-
charge
Outdoor coil dirty or restricted Clean coil or remove restriction
Excessive head pressure
Dirty air filter Replace filter
Dirty indoor or outdoor coil Clean coil
Refrigerant overcharged Recover excess refrigerant
Air in system
Recover refrigerant, evacuate system, and re-
charge
Indoor or outdoor air restricted or air short--cycling Determine cause and correct
Head pressure too low
Low refrigerant charge Check for leaks, repair and recharge
Restriction in liquid tube Remove restriction
Excessive suction pressure Refrigerant overcharged Recover excess refrigerant
Suction pressure too low
Dirty air filter Replace filter
Low refrigerant charge Check for leaks, repair and recharge
Metering device or low side restricted Remove source of restriction
Insufficient coil airflow Check filter–replace if necessary
Temperature too low in conditioned area Reset thermostat setting
Outdoor ambient below 55°F (13°C) Install low--ambient kit
Filter drier restricted Replace
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