Carrier 48EZ(N)-A Installation Instructions Manual page 39

Table 12 – Troubleshooting Guide - - Cooling or Heat Pump Heating Mode
SYMPTOM
Compressor and Outdoor fan will not
start.
Compressor will not start but Outdoor
fan runs.
Three --- phase scroll compressor makes
excessive noise, and there may
be a low pressure differential.
Compressor cycles (other than normally
satisfying thermostat).
Compressor operates continuously.
Excessive head pressure.
Head pressure too low.
Excessive suction pressure.
Suction pressure too low.
Compressor runs but outdoor fan does
not
CAUSE
Power Failure
Fuse blown or circuit breaker tripped
Defective thermostat, contactor, 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 over-
load open
Defective run/start capacitor, overload, start relay
One leg of 3 ---phase power dead
Scroll compressor is rotating in the wrong direction
Refrigerant overcharge or undercharge
Defective compressor
Insufficient line voltage
Blocked Outdoor
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
Mechanical damage in compressor.
Air in system
Frosted coil with incorrect defrost operation
Outdoor coil dirty or restricted
Dirty air filter
Dirty Indoor or Outdoor coil
Refrigerant overcharged
Air in system
Indoor or Outdoor air restricted or air short---cycling
Low refrigerant charge
Compressor IPR leaking
Restriction in liquid tube
High heat load
Compressor IPR leaking
Refrigerant overcharged
Reversing valve hung up or leaking internally
Dirty air filter
Low refrigerant charge
Metering device or low side restricted
Insufficient Indoor airflow
Temperature too low in conditioned area
Outdoor ambient below 55°F (12.8°C)
Field---installed filter ---drier restricted
(Heat) Outdoor coil frosted
NC (normally closed) contacts on defrost board open
39
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.
Replace fuse or reset circuit breaker. Determine
cause.
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.
Replace compressor.
Recover refrigerant, evacuate system, and recharge.
Check defrost time settings, Reset as necessary
Check defrost temperature switch, Replace as nec-
essary
Clean coil or remove restriction .
Replace filter.
Clean coil.
Recover excess refrigerant.
Recover refrigerant, evacuate system, and recharge.
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 valve
Replace Filter.
Check for leaks, repair, and recharge.
Remove source of restriction.
Increase air quantity. Check filter — replace if neces-
sary.
Reset thermostat.
Install low---ambient kit.
Replace.
Move timer on control board to 30 minutes between
defrost cycles
Check condition of relay on board Replace if neces-
sary