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Lennox Fhm 170 Installation, Operating And Maintenance Guide

Lennox Fhm 170
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MAINTENANCE DIAGNOSTIC
FLEXYII_WSHP-IOM-1307-E - 74 -
REFRIGERATION
FAULT POSSIBLE CAUSE AND SYMPTOMS SOLUTION
HP PROBLEMS AND HP CUT
OUTS
Incorrect airflow rates
Heat pump mode:
Check the filter before the indoor coil
measure and estimate the airflow rate
increase the speed of the fan
Cooling mode:
Check the condenser fan (Amps)
Incorrect water flow rate (Water cooled
rooftop only)
Check water flow value
Moisture or contaminants in the
system
Summer operation
Several hours after the unit has
stopped, check the correspondence
between the measured pressure and
the outdoor temperature
If the circuit pressure is higher (<1bar)
than the saturated pressure
corresponding to the measured
outdoor temperature, there is
possibility that some contaminants are
present in the system.
Reclaim the refrigerant, and vacuum
the circuit (Ensure very low and slow
vacuum for R407c)
Recharge the unit
Condenser coil is obstructed
Check the condenser coil and clean is
necessary
Water Filter is obstructed
(only for Water Cooled Rooftop)
Check the water filter and clean if
necessary
Recycled Hot Air
Check clearance around the
condenser
Strong variations of pressure (
2 to 3 bar) Thermostatic
Expansion Valve "hunting"
Incorrect adjustment of the expansion
valve
Refer to LP problems and LP cut out
section
Low refrigerant charge
Filter drier obstructed with gas bubbles
at the expansion valve inlet
Moisture in the system
Very high discharge
temperature,
High amps measured at
compressor
Very high superheat, very hot
compressor
Open the superheat adjustment on the
expansion valve.
Check the pressure drop on the filter
drier in the suction line
Four Way reversing valve possibly
blocked, abnormal noise from the
valve, low LP and increasing HP
Check operation of the valve by going
through cycle inversions. Change if
necessary.
Refer to LP problems

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Lennox Fhm 170 Specifications

General IconGeneral
BrandLennox
ModelFhm 170
CategoryHeat Pump
LanguageEnglish

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