38
TROUBLESHOOTING
Refer to Table 14 to determine the possible cause of the
problem and the associated procedure necessary to correct it.
See Fig. 34 and 35 for typical wiring.
Table 14 — Troubleshooting Procedure
LEGEND
PROBLEM
POSSIBLE CAUSE
CORRECTION PROCEDURE
Unit will not start
Loss of unit power
Check power source.
Check fuses, circuit breakers, disconnect switch.
Check electrical contacts.
Unit voltage not correct
Check and correct.
Open fuse
Check for short circuit in unit.
Open protection device
Check relays, contacts, pressure switches.
Unit or motor contactor out of order
Test and replace if necessary.
Fan does not operate
Contactor or relay overload or out of order
Test and replace if necessary.
Motor defective
Test and replace if necessary.
Broken belt
Replace belt.
Loose electrical contact
Tighten contact.
Compressor is noisy, but
will start
Under voltage
Check and correct.
Defect in compressor motor
Replace compressor.
Missing phase
Check and correct.
Compressor seized
Check and replace if necessary.
Compressor starts, but
does not continue to run
Compressor or contact defect
Test and replace if necessary.
Unit is not properly charged
Check and correct any leaks. Adjust refrigerant charge.
Unit is oversized
Check load calculation.
Compressor is overloaded
Check protection device and replace.
Check for missing phase.
Check TXV.
Check temperature in suction discharge line.
Unit is noisy
Compressor noise
Check TXV and replace if necessary.
Check internal noise.
Tube vibration or condenser water problem
Check and correct.
Unit panel or part vibrating
Check and tighten appropriate part.
Unit runs continuously,
but has low capacity
Unit is undersized
Check heat load calculation.
Low refrigerant or noncondensing gas present
Check for leaks and add refrigerant or gas as necessary.
Replace refrigerant if noncondensing gas present.
Compressor defect
Check pressure and amps. Replace if necessary.
Insufficient flow of refrigerant in evaporator
Check filter drier and replace if necessary.
Check TXV and adjust or replace if necessary.
Check position of TXV bulb and equalizer.
Low airflow
Check filters, and clean or replace as necessary.
Check coils, and clean as necessary.
Check for restrictions in ductwork.
Check fan rotation and adjust.
Check fan motor.
Check belts for wear.
Oil in evaporator
Drain evaporator.
Unit has high discharge
pressure
Low airflow in condenser
Check fan rotation.
Check motor, and replace if necessary.
Check belts, and replace if necessary.
Check coils, and clean if necessary.
Scale in condenser coil
Clean condenser.
High temperature in condenser air or air
recirculation
Check for short circuit of air.
Check water supply installation.
Overcharged
Check and recover excess charge.
Adjust subcooling.
Water connections reversed
Verify and correct.
Noncondensing gas present
Verify and correct.
Replace refrigerant.
TXV —
Thermostatic Expansion Valve
