Carrier 50ZH024-060 - Manual (Page 19)

Cooling and Heating Troubleshooting Chart (cont)
SYMPTOM CAUSE REMEDY
Excessive head
pressure. Dirty air filter Replace filter.
Dirty indoor or outdoor coil Clean coil.
Refrigerant overcharged Recover excess refrigerant.
Air in system Recover refrigerant, evacuate system, and recharge.
(Heat) Indoor air restricted or recirculating Determine cause and correct.
Indoor or outdoor air restricted or
air short-cycling Determine cause and correct.
Head pressure too low. Low refrigerant charge Check for leaks, repair and recharge.
Compressor valves leaking Replace compressor.
Restriction in liquid tube Remove restriction.
Excessive suction
pressure. (Heat) Outdoor coil frosted Move timer on control board to 30 minutes
between defrost cycles.
(Cool) High heat load Check for source and eliminate.
Compressor valves leaking Replace compressor.
Reversing valve hung up or leaking internally Replace valve.
Refrigerant overcharged Recover excess refrigerant.
Suction pressure too
low. (Cool) Dirty air filter Replace filter.
(Heat) Outdoor coil frosted Move timer on control board to 30 minutes
between defrost cycles.
Low refrigerant charge Check for leaks, repair and recharge.
Metering device or low side restricted Remove source of restriction.
(Cool) Insufficient coil airflow Increase air quantity. Check filter — replace if
necessary.
(Cool) Temperature too low in conditioned area Reset thermostat.
(Cool) Outdoor ambient below 40 F Install low-ambient kit.
Field-installed filter drier restricted Replace.
Compressor runs but
outdoor fan does not. Normally closed contacts on defrost board open Check condition of relay on board. Replace if necessary.
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