Carrier 48NLT - Manual (Page 22)

Table 12 — Cooling Troubleshooting Chart
SYMPTOM CAUSE REMEDY
Cpmpressor and con-
denser fan will not
start. Power failure Call power company
Fuse blown or circuit breaker tripped Replace fuse or reset circuit breaker.
Defective thermostat, contactor, transformer or
control
relay Replace component.
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 temperature
Compressor will not
start but condenser
fan runs.
Faulty wiring or loose connections in compres­
sor circuit Check wiring and repair or replace.
Compressor motor burner out, seized or internal
overload open Determine cause. Replace compresor.
Defective run/start capacitor, overload, start re­
lay Determine cause and replace.
One leg of 3-phase power dead Replace fuse or reset circuit breaker.
Determine cause.
Compressor cycles
(other than normally
satisfying thermostat).
Refrigerant overcharge or undercharge Blow refrigerant, evacuate system and recharge to nameplate.
Defective compressor Replace and determine cause
Insufficient line voltage Determine cause and correct
Blocked condenser Determine cause and correct.
Defective run/start capacitor, overload or start
relay Determine cause and replace.
Defective thermostat Replace thermostat.
Faulty condenser fan motor or capacitor Replace.
Restriction in refrigerant system Locate restriction and remove.
Compressor operates
continuously. 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.
Leaking valves in compressor Replace compressor.
Air in system Blow refrigerant, evacuate system and recharge.
Condenser coil dirty or restricted Clean coil or remove restriction.
Excessive head pres-
sure. Dirty air filter Replace filter.
Dirty condenser coil Clean coil.
Refrigerant overcharged Purge excess refrigerant.
Air in system Blow refrigerant, evacuate system and recharge.
Condenser 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.
High heat load Check for source and eliminate.
Compressor valves leaking Replace compressor
Refrigerant overcharged Purge excess refrigerant.
Suction pressure too
low. Dirty air filter Replace filter
Low refrigerant charge Check for leaks, repair and recharge.
Metering device or low side restricted Remove source of restriction.
Insufficient evaporator airfiow Increase air quantity. Check filter — replace if
necessary.
Temperature too low in conditioned area Reset thermostat.
Outdoor ambient below 55 F Install low-ambient kit.
Field-installed filter-drier restricted Replace.
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