Carrier 50JZ Installation, Start-Up And Service Instructions Manual page 27

SYMPTOM
Compressor and outdoor fan
will not start
Compressor will not start but condenser fan
runs
Three-phase scroll compressor
may be a low pressure differential
Compressor cycles (other than normally
satisfying thermostat)
Compressor operates continuously
Excessive head pressure
(Continued next page)
Table 15—Troubleshooting Chart
CAUSE
Power Failure
Fuse blown or circuit breaker tripped
Defective thermostat, contactor, transformer,
control relay, defrost board, or high pressure or loss-
of-charge/low pressure switch
Insufficient line voltage
Incorrect or faulty wiring
Thermostat setting too high
Units have a 5-minute time delay
Phase Monitor
Faulty wiring or loose connections in compressor
circuit
Compressor motor burned out, seized, or
internal overload open
Defective overload
One leg of 3-phase power dead
Low input voltage (20 percent low)
Power Leads running out of phase
Scroll compressor is rotating in the wrong
direction
Refrigerant overcharge or undercharge
Defective compressor
Insufficient line voltage
Blocked outdoor coil
Defective overload
Defective thermostat
Faulty outdoor-fan motor
Damaged reversing valve
Restriction in refrigerant system
Dirty air filter
Unit undersized for load
Thermostat set too low
Low refrigerant charge
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
(Heating) Indoor air restricted or recirculating
(Cooling) outdoor air restricted or recirculating
27
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 minutes until time-delay
relay is deenergized
Correct inoorrect power supply
Check wiring and repair or replace
Determine cause.
Replace compressor
Determine cause and replace
Replace fuse or reset circuit breaker. Determine
cause
Determine cause and correct
Change 2 Leads or 3 Phase Power Supply
Correct the direction of rotation by reversing the
3-phase power leads to the unit
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
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