18
Unit not cooling. (Temperature
Failed Evaporator Blower.
Check Blower wire connections.
difference between return and
Check blower capacitor.
supply air is less than 10°F).
Replace Evaporator Blower.
Compressor and Condenser Blower
are running. Evaporator Blower does
not run.
Unit not cooling. (Temperature
Low Refrigerant charge.
Check discharge and suction pressure for
difference between return and
Refrigerant leak.
supply air is less than 10°F).
Failed Condenser Blower.
Check Blower wire connections.
Compressor and Evaporator Blower
Check Blower Capacitor.
are running. Condenser Blower does
Replace Condenser Blower.
not run.
Failed Speed Controller.
Check Speed Controller Sensor.
Replace Speed Controller.
Unit not cooling. (Temperature
Condenser or Evaporator
Clean Coil.
difference between return and
Coil clogged.
supply air is less than 10°F).
Evaporator Blower, Condenser
Loss of Refrigerant.
Locate and repair leak.
Blower and Compressor are running.
Ice on Evaporator Coil.
Clean Evaporator Coil.
Check discharge and suction pressure for
Refrigerant leak.
Check for any obstruction of Evaporator airflow.
Check and seal all openings.
Excessive condensate
Eliminate the frequency of door openings.
draining and loss of A/C
sensible cooling performance.
Unit overcooling.
Failed Thermostat.
Check Thermostat wire connections
.
Evaporator Blower, Condenser
Replace Thermostat.
Blower and Compressor are running.
Failed Relay.
Replace Relay.
Compressor cycling more than
Short circuiting of air
Provide baffle in the enclosure separating A/C
10 cycles per hour.
between A/C discharge
Outlet and inlet.
and inlet openings.
Excess vibration.
Defective motor in Blower.
Replace motor.
Defective wheel in Blower.
Replace wheel.
Bad Compressor.
Replace Compressor.
.
Trouble-Shooting (con’t)
Problem
Cause
Solution
Compressor and Condenser
Return temperature is
Normal Operation.
Blower do not run when initially
between Thermostat set
energized after 15 minutes.
point and differential
(
75°F to 86°F).
Unit not cooling. (Temperature
Failed Thermostat
Check Thermostat and Relay wire connections.
difference between return and
or Relay.
Replace Thermostat or Relay.
supply air is less than 10°F).
Evaporator Blower is running.
Low Line Voltage.
Check Nameplate Voltage against supply Voltage.
Compressor and Condenser Blower
do not run. Return temperature is
Failed Compressor.
Check Compressor wire connections.
above set point plus differential (90°F).
Check Compressor overload.
Check Compressor Capacitor.
Replace Compressor.
