Troubleshooting The Cooling System - Carrier 50TC*17 Series Service And Maintenance Instructions

TROUBLESHOOTING THE COOLING SYSTEM

Refer to Table 5 for additional troubleshooting topics.
PROBLEM
Compressor and Con­
denser Fan Will Not Start.
Compressor Will Not
Start But Condenser Fan
Runs.
Compressor Cycles
(other than normally
satisfying thermostat).
Compressor Operates
Continuously.
Excessive Head
Pressure.
Faulty TXV valve.
Head Pressure Too Low.
Excessive Suction
Pressure.
Faulty TXV valve.
Suction Pressure Too
Low.
Evaporator Fan Will Not
Shut Off.
Compressor Makes
Excessive Noise.
Table 5 – Cooling Service Troubleshooting
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 compres­
sor circuit.
Compressor motor burned out, seized, or
internal overload open.
Defective run/start capacitor, overload, start
relay.
One leg of three-phase power dead.
Refrigerant overcharge or undercharge.
Defective compressor.
Insufficient line voltage.
Blocked condenser.
Defective run/start capacitor, overload, or start
relay.
Defective thermostat.
Faulty condenser-fan motor or capacitor.
Restriction in refrigerant system.
Dirty air filter.
Unit undersized for load.
Thermostat set too low.
Low refrigerant charge.
Leaking valves in compressor.
Air in system.
Condenser coil dirty or restricted.
Dirty air filter.
Dirty condenser coil.
Refrigerant overcharged.
Air in system.
Condenser air restricted or air short-cycling.
Low refrigerant charge.
Compressor valves leaking.
Restriction in liquid tube.
High head load.
Compressor valves leaking.
Refrigerant overcharged.
Dirty air filter.
Low refrigerant charge.
Metering device or low side restricted.
Insufficient evaporator airflow.
Temperature too low in conditioned area.
Outdoor ambient below 25°F.
Time off delay not finished.
Compressor rotating in wrong direction.
REMEDY
Call power company.
Replace fuse or reset circuit breaker.
Replace defective component.
Determine cause and correct.
Check wiring diagram and rewire correctly.
Lower thermostat setting below room temperature.
Check wiring and repair or replace. Tighten loose connec­
tions.
Determine cause. Replace compressor.
Determine cause and replace defective component.
Replace fuse or reset circuit breaker. Determine cause.
Recover refrigerant, evacuate system, and recharge to
values on nameplate.
Replace defective compressor.
Determine cause and correct.
Determine cause and correct.
Determine cause and replace.
Replace thermostat.
Replace. Defective fan motor or capacitor.
Locate restriction and remove.
Replace filter.
Decrease load or replace with larger unit.
Reset thermostat.
Locate leak; repair and recharge.
Replace compressor.
Recover refrigerant, evacuate system, and recharge.
Clean coil or remove restriction.
Replace air filter.
Clean condenser coil.
Recover excess refrigerant.
1. Check TXV bulb mounting and secure tightly to suction
line and insulate.
2. Replace TXV valve and filter drier if stuck open or closed.
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 filter.
Check for leaks; repair and recharge.
Remove source of restriction.
1. Check TXV bulb mounting and secure tightly to suction
line and insulate.
2. Replace TXV valve and filter drier if stuck open or closed.
Increase air quantity. Check filter and replace if
necessary. Check belt tension on blower.
Reset thermostat.
Install low-ambient kit.
Wait for 30-second off delay.
Reverse the 3-phase power leads.
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