Troubleshooting Cooling System - Carrier WeatherExpert 50LC 07 Series Service And Maintenance Instructions

Fig. 9 — Condenser Fan Adjustment
PROBLEM
Compressor and Condenser
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
Head Pressure Too Low
Excessive Suction Pressure
Suction Pressure Too Low
Evaporator Fan Will Not
Shut Off
Compressor Makes
Excessive Noise
CONDUIT
0.14 in. + 0.0 / -0.03
Table 1 — Cooling Service Analysis
CAUSE
Power failure.
Fuse blown or circuit breaker tripped.
Defective thermostat, contactor, transformer, or control relay. Replace component.
Insufficient line voltage.
Incorrect or faulty wiring.
Thermostat setting too high.
Faulty wiring or loose connections in compressor 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 heat 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.

Troubleshooting Cooling System

Refer to Table 1 for additional troubleshooting topics.
Call power company.
Replace fuse or reset circuit breaker.
Determine cause and correct.
Check wiring diagram and rewire correctly.
Lower thermostat setting below room temperature.
Check wiring and repair or replace.
Determine cause. Replace compressor.
Determine cause and replace.
Replace fuse or reset circuit breaker. Determine
cause.
Recover refrigerant, evacuate system, and recharge
to nameplate.
Replace and determine cause.
Determine cause and correct.
Determine cause and correct.
Determine cause and replace.
Replace thermostat.
Replace.
Locate restriction and remove.
Replace filter.
Decrease load or increase unit size.
Reset thermostat.
Locate leak; repair and recharge.
Replace compressor.
Recover refrigerant, evacuate system, and
recharge.
Clean coil or remove restriction.
Replace filter.
Clean coil.
Recover excess refrigerant.
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.
Increase air quantity. Check filter and replace if
necessary.
Reset thermostat.
Install low-ambient kit.
Wait for 30-second off delay.
Reverse the 3-phase power leads.
8
REMEDY