Carrier 48KH - Manual (Page 23)

TROUBLESHOOTING CHART
Table 9 — Cooling Service Analysis Chart
SYMPTOM PROBABLE CAUSE REMEDY
Compressor and con­
denser fan will not start Power failure
Fuse blown or circuit breaker
tripped
Call power company
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 compressor circuit Check wiring and repair or replace
Compressor motor burned out,
seized, or internal overload open Determine cause Replace compressor.
Defective run/start capacitor,
overload, start relay
Determine cause and replace
One leg of 3-phase power dead Determine cause
Replace fuse or reset circuit breaker
Compressor cycles (other
than normally satisfying
Refrigerant overcharge or
undercharge Blow refrigerant, evacuate system, and recharge to
nameplate
thermostat)
Defective compressor Determine cause, replace
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 Replace
capacitor
Restriction in refrigerant system Locate restriction and remove
Compressor operates
continuously
Dirty air filter
Unit undersized for load
Replace filter
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 pressure Dirty air filter Replace filter
Dirty condenser coil Clean coil
Refrigerant overcharged Purge excess refrigerant.
Áir 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 Fligh heat load Check for source and eliminate
Compressor valves leaking Replace compressor
Refrigerant overcharged Purge excess refrigerant.
Suction pressure too low Dirty air filter
Low refrigerant charge
Replace filter
Check for leaks, repair, and recharge
Metering device or low side
restricted Remove source of restriction.
Insufficient evaporator airflow Increase a ir quantity Check filter — replace if necessary
Temperature too low in condi­
tioned area Reset thermostat
Outdoor ambient below 55 F Install accessory low-ambient kit
Field-installed filter drier
restricted Replace.
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