Carrier 50GX User Manual
Table 10—Troubleshooting—Cooling
SYMPTOM
CAUSE
REMEDY
Compressor and condenser fan will not start.
Power Failure
Call power company
Fuse blown or circuit breaker tripped
Replace fuse or reset circuit breaker
Defective thermostat, contractor, transformer, or
control relay
Replace component
Insufficient line voltage
Determine cause and correct
Incorrect or faulty wiring
Check wiring diagram and rewire correctly
Thermostat setting too high
Lower thermostat setting below
room temperature
Compressor will not start but condenser fan
runs.
Faulty wiring or loose connections in compressor
circuit
Check wiring and repair or replace
Compressor motor burned out, seized, or internal
overload open
Determine cause
Replace compressor
Defective run/start capacitor, overload, start relay
Determine cause and replace
One leg of 3-phase power dead
Replace fuse or reset circuit breaker
Determine cause
Three-phase scroll compressor (50GS048,
50GX030-060) makes excessive noise, and
there may be a low pressure differential.
Scroll compressor is rotating
in the wrong direction
Correct the direction of rotation by reversing the
3-phase power leads to the unit. Shut down unit
to allow pressures to equalize.
Compressor cycles
(other than normally satisfying thermostat).
Refrigerant overcharge or undercharge
Recover refrigerant, evacuate system, and re-
charge to capacities shown on nameplate
Defective compressor
Replace and determine cause
Insufficient line voltage
Determine cause and correct
Blocked condenser
Determine cause and correct
Defective run/start capacitor, overload or start
relay
Determine cause and replace
Defective thermostat
Replace thermostat
Faulty condenser-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 set too low
Reset thermostat
Low refrigerant charge
Locate leak, repair, and recharge
Leaking valves in compressor
Replace compressor
Air in system
Recover refrigerant, evacuate system, and re-
charge
Condenser coil dirty or restricted
Clean coil or remove restriction
Excessive head pressure.
Dirty air filter
Replace filter
Dirty condenser coil
Clean coil
Refrigerant overcharged
Recover excess refrigerant
Air in system
Recover refrigerant, evacuate system, and re-
charge
Condenser air restricted or air short-cycling
Determine cause and correct
Head pressure too low.
Low refrigerant charge
Check for leaks, repair and recharge
Compressor valves leaking
Replace compressor
Restriction in liquid tube
Remove restriction
Excessive suction pressure.
High heat load
Check for source and eliminate
Compressor valves leaking
Replace compressor
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 evaporator airflow
Increase air quantity
Check filter- replace if necessary
Temperature too low in conditioned area
Reset thermostat
Outdoor ambient below 40°F
Install low-ambient kit
Field-installed filter-drier restricted
Replace
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