Carrier 50SD Install And Operation Instructions page 18

SYMPTOM
Compressor and condenser fan will not start.
Compressor will not start but condenser fan
runs.
Compressor cycles
(other than normally satisfying thermostat).
Compressor operates continuously.
Excessive head pressure.
Head pressure too low.
Excessive suction pressure.
Suction pressure too low.
Table 6—Troubleshooting—Cooling
CAUSE
Power Failure
Fuse blown or circuit breaker tripped
Defective thermostat, contractor, transformer, or
control relay
Insufficient line voltage
Incorrect or faulty wiring
Thermostat setting too high
Faulty wiring or loose connections in compressor
circuit
Compressor motor burned out, seized, or internal
overload open
Defective run/start capacitor, overload, start relay
Refrigerant overcharge or undercharge
Defective compressor
Insufficient line voltage
Blocked condenser
Defective run/start capacitor, overload or start
relay
Defective thermostat
Faulty condenser-fan motor or capacitor
Restriction in refrigerant system
Dirty air filter
Unit undersized for load
Thermostat set too low
Low refrigerant charge
Leaking valves in compressor
Air in system
Condenser coil dirty or restricted
Dirty air filter
Dirty condenser coil
Refrigerant overcharged
Air in system
Condenser air restricted or air short-cycling
Low refrigerant charge
Compressor valves leaking
Restriction in liquid tube
High heat load
Compressor valves leaking
Refrigerant overcharged
Dirty air filter
Low refrigerant charge
Metering device or low side restricted
Insufficient evaporator airflow
Temperature too low in conditioned area
Outdoor ambient below 40°F
Field-installed filter-drier restricted
18
REMEDY
Call power company
Replace fuse or reset circuit breaker
Replace component
Determine cause and correct
Check wiring diagram and rewire correctly
Lower thermostat setting below
room temperature
Check wiring and repair or replace
Determine cause
Replace compressor
Determine cause and replace
Recover refrigerant, evacuate system, and re-
charge to capacities shown on nameplate
Replace and determine cause
Determine cause and correct
Determine cause and correct
Determine cause and replace
Replace thermostat
Replace
Locate restriction and remove
Replace filter
Decrease load or increase unit size
Reset thermostat
Locate leak, repair, and recharge
Replace compressor
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
Replace compressor
Remove restriction
Check for source and eliminate
Replace compressor
Recover excess refrigerant
Replace Filter
Check for leaks, repair, and recharge
Remove source of restriction
Increase air quantity
Check filter- replace if necessary
Reset thermostat
Install low-ambient kit
Replace