Failure Diagnosis - Lennox FLATAIR FMC-H Installation, Operating And Maintanance Manual

4.- MAINTENANCE

4.3.- FAILURE DIAGNOSIS

In case of failure or malfunction of the unit, the display on the control panel will show an error or alarm warning which
is explained in the control panel manual. Nevertheless, whenever there is a unit fault, the unit should be shut down and
our service technicians consulted.
FAULT
UNIT DOES NOT START
UNIT STOPS DUE TO HIGH
PRESSURE DURING THE
COOLING CYCLE
UNIT STOPS DUE TO HIGH PRESSU-
RE DURING THE HEATING CYCLE
UNIT STOPS DUE TO LOW
PRESSURE
UNIT STARTS AND STOPS IN
SHORT CYCLES
LOAD AND ABNORMAL NOISE IN
THE COMPRESSOR (SCROLL)
POSSIBLE CAUSES
Fault in the power supply or insufficient voltage.
Circuit breakers have opened.
Power cable or control panel cable is defective.
High pressure switch is defective.
Outdoor fan is not working.
Outdoor fan turns in the wrong direction.
Outdoor coil is dirty or clogged for passing air.
Excess refrigerant charge.
The same causes and solutions as the cold cycle but with reference to the coils and indoor fan.
Low pressure switch defective.
Indoor fan is not working.
Indoor fan turns in the wrong direction.
Lack of refrigerant. Leak.
Dirty air filter.
Clogged cooling circuit.
Dirty filter drier.
Compressor overcharged.
Compressor cuts off due to Klixon.
Lack of refrigerant.
Power supply phases inverted.
(three-phase compressor).
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POSSIBLE SOLUTIONS
Connect the power supply or check the voltage.
Reset.
Inspect and correct.
Check cut-off pressure switch or replace
pressure switch if necessary.
Check for voltage, inspect the motor and turbine
or replace if necessary..
Reverse the power phases.
Inspect and clean.
Remove the charge and charge according to the
data on the rating plate.
Check the cut-off pressure with a pressure gauge
and replace the pressure switch if necessary.
Check for voltage and inspect the motor, turbine
and replace if necessary.
Reverse the power phases.
Correct leak, create vacuum and charge.
Inspect and clean
Inspect and correct or change the filter drier.
Inspect suction and discharge pressure values
and correct.
Check input voltage and voltage drop.
Correct leak and replace.
Check and reverse power phases.