Carrier 50SZ Series Installation, Start-Up And Service Instructions Manual page 19

SYMPTOM
Compressor and outdoor
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
(Continued next page)
Table 9—Cooling and Heating Troubleshooting Chart
Power Failure
Fuse blown or circuit breaker tripped
Defective thermostat, contractor, transformer,
control relay or defrost board
Insufficient line voltage
Incorrect or faulty wiring
Thermostat setting too high
Units have a 5-minute time delay
Faulty wiring or loose connections in compressor
circuit
Compressor motor burned out, seized, or
internal overload open
Defective run capacitor, overload, or PTC
(positive temperature coefficient) thermistor
Defective run capacitor, overload, or PTC (positive temperature co-
efficient) thermistor
Refrigerant overcharge or undercharge
Defective compressor
Insufficient line voltage
Blocked outdoor coil
Defective run/start capacitor, overload or start
relay
Defective thermostat
Faulty outdoor-fan motor or capacitor
Damaged reversing valve
Restriction in refrigerant system
Dirty air filter
Unit undersized for load
Thermostat set too low
Low refrigerant charge
Leaking valves in compressor
Frosted coil with incorrect defrost operation
Air in system
Outdoor coil dirty or restricted
Dirty air filter
Dirty indoor or outdoor coil
Refrigerant overcharged
Air in system
(Heat) Indoor air restricted or recirculating
Indoor or outdoor air restricted or air short-cycling
Low refrigerant charge
Compressor valves leaking
Restriction in liquid tube
(Heat) Outdoor coil frosted
(Cool) High Heat load
Compressor valves leaking
Reversing valve hung up or leaking internally
Refrigerant overcharged
CAUSE
19
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
DO NOT bypass this compressor time
delay-wait for 5 minute until time-delay relay is
de-energized
Check wiring and repair or replace
Determine cause.
Replace compressor
Determine cause and replace
Determine cause and replace
Recover refrigerant, evacuate system, and
recharge to capacities shown on nameplate
Replace and determine cause
Determine cause and correct
Determine cause and correct
Determine cause and replace
Replace thermostat
Replace
Determine cause and correct
Locate restriction and remove
Replace filter
Decrease load or increase unit size
Reset thermostat
Locate leak, repair, and recharge
Replace compressor
Check defrost time settings
Reset as necessary
Check defrost temperature switch
Replace as necessary
Recover refrigerant, evacuate system,
and recharge
Clean coil or remove restriction
Replace filter
Clean coil
Recover excess refrigerant
Recover refrigerant, evacuate system,
and recharge
Determine cause and correct
Determine cause and correct
Check for leaks, repair and recharge
Replace compressor
Remove restriction
Move timer on control board to 30 minute between
defrost cycles
Check for source and eliminate
Replace compressor
Replace valve
Recover excess refrigerant