Table 8ÐTroubleshootingÐCooling and Heating

SYMPTOM

CAUSE

REMEDY

 

 

 

 

Power Failure

Call power company

 

Loss of Charge

Evaluate unit for possible refrigerant leak

 

Switch open

 

 

 

Fuse blown or circuit breaker tripped

Replace fuse or reset circuit breaker

 

 

 

Compressor and outdoor fan will not start.

Defective thermostat, contractor, transformer, or

Replace component

control relay

 

 

 

 

 

 

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 tempera-

 

ture

 

 

 

Faulty wiring or loose connections in compressor

Check wiring and repair or replace

 

circuit

 

 

 

 

 

 

Compressor motor burned out, seized, or internal

Determine cause

Compressor will not start but outdoor fan

overload open

Replace compressor

 

 

Defective run/start capacitor, overload, start relay

Determine cause and replace

runs.

One leg of 3-phase power dead

Replace fuse or reset circuit breaker

 

 

Determine cause

 

 

 

Low input voltage

Determine cause and correct

 

(20 percent low)

 

 

 

Refrigerant overcharge or undercharge

Recover refrigerant, evacuate system, and re-

 

charge to capacities shown on nameplate

 

 

 

Loss of Charge

Evaluate unit for possible refrigerant leak

 

Switch open

 

 

 

Defective compressor

Replace and determine cause

Compressor cycles

Insufficient line voltage

Determine cause and correct

 

 

(other than normally satisfying thermostat).

Blocked outdoor coil (cooling)

Determine cause and correct

 

 

 

 

Defective run/start capacitor, overload or start

Determine cause and replace

 

relay

 

 

 

 

 

 

Defective thermostat

Replace thermostat

 

Faulty outdoor-fan motor or capacitor

Replace

 

 

 

 

Restriction in refrigerant system

Locate restriction and remove

 

 

 

 

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

 

 

 

Compressor operates continuously.

Leaking valves in compressor

Replace compressor

 

Frosted outdoor coil with incorrect

Check defrost time settings. Reset as necessary.

 

defrost operation (heating)

Check defrost temperature switch. Replace as necessary.

 

Air in refrigerant system

Recover refrigerant, evacuate system, and re-

 

charge

 

 

 

outdoor coil dirty or restricted

Clean coil or remove restriction

 

 

 

 

Dirty air filter

Replace filter

 

 

 

 

Dirty outdoor coil

Clean coil

Excessive head pressure.

Refrigerant overcharged

Recover excess refrigerant

 

 

Air in refrigerant system

Recover refrigerant, evacuate system, and re-

 

 

charge

 

 

 

Outdoor or indoor air restricted

Determine cause and correct

 

or air is recirculating

 

 

 

Low refrigerant charge

Check for leaks, repair and recharge

Head pressure too low.

 

 

Compressor valves leaking

Replace compressor

 

 

 

 

Restriction in liquid tube

Remove restriction

 

High heat load

Check for source and eliminate

Excessive suction pressure.

 

 

Compressor valves leaking

Replace compressor

 

 

 

 

Refrigerant overcharged

Recover excess refrigerant

 

Dirty air filter (cooling)

Replace Filter

 

 

 

 

Low refrigerant charge

Check for leaks, repair, and recharge

 

 

 

 

Metering device or low side restricted

Remove source of restriction

Suction pressure too low.

Insufficient indoor airflow (cooling)

Increase air quantity

Check filter- replace if necessary

 

 

 

 

 

 

Temperature too low in conditioned area (cooling)

Reset thermostat

 

Outdoor ambient below 40°F (cooling)

Install low-ambient kit

 

 

 

 

Field-installed filter-drier restricted

Replace

 

 

 

Compressor runs but

Normally closed contacts on

Check condition of relay on board.

outdoor fan does not.

defrost board open

Replace board if necessary.

 

 

 

22

Page 22
Image 22
Carrier 50ZH024-060 instruction manual ÐTroubleshootingÐCooling and Heating, Symptom Cause Remedy