Maintenance Diagnostic - Lennox FLEXY II Series Installation, Operating And Maintenance

MAINTENANCE DIAGNOSTIC

REFRIGERATION
FAULT
between T outdoor and Tev ap. (Dew) is too high
LP PROBLEMS and
LP CUT OUTS
HP PROBLEMS AND
HP CUT OUTS
IOM – FLEXY II – 1007 – E
POSSIBLE CAUSE AND SYMPTO MS
Ref rigerant charge too low
In Heat Pump Mode the temperature difference
5°C < Delta T < 10°C excellent
10°C < Delta T < 15°C acceptable
15°C < Delta T < 25°C too high
Ref rigeration circuit blocked in distribution
Liquid line drier blocked. High temperature
difference between inlet and outlet of the drier
Contaminant in the expansion valv e
Expansion valv e not adjusted properly
Ice plug in the expansion v alve.
Incorrect insulation of the thermostatic bulb of
the expansion valv e
Low Pressure Switch cut out point too high
LP cut out due to not enough def rost on heat
pumps
Incorrect Airflow rates
Moisture or contaminants in the system
SOLUTION
Measure the superheat and sub-cooling:
Good if 5°C<SC<10°C and 5°C<SH<10°C
Bad if SC>10°C and SH too Low
Check superheat adjustment and charge unit (a
leak check must be carried out)
If too high check the coils are clean or check coil
internal pressure drop between the liquid line and
the suction line
Good if < 3bar
Too high if > 3bar (coil blocked)
Stop the f an and create icing of the coil.
Check all circuits f reeze evenly across the whole
surf ace of the coil
If some parts of the coil do not f reeze this could
indicate a problem with the distribution
Change f ilter drier
Attempt to free the valv e adjusting element by
freezing the valv e and then heating the
thermostatic element. Replace the v alve if
necessary
Adjust the expansion Valv e
Heat the main body of the valv e. If the LP
increases and then decreases gradually, empty
the circuit and replace the drier.
Superheat too low: adjust superheat
Mov e the thermostatic element along the pipe
Insulate the Thermostatic element of the v alve
Check the cut out pressure of the Low Pressure
switch: It must be 0.7+/- 0.2bar and must closes
at 2.24 +/- 0.2 bar
Adjust the CLIMATIC settings to extend the
def rost cycles or shorten the time between
def rosts
Heat pump mode:
Check the f ilter before the indoor coil
measure and estimate the airflow rate
increase the speed of the fan
Cooling mode:
Check the condenser fan (Amps)
Summer operation
Sev eral hours after the unit has stopped, check
the correspondence between the measured
pressure and the outdoor temperature
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