IOM / ROOFTOP BALTIC Series - 0704-E Page 143
maintenance diagnostic
FAULT
HP PROBLEMS AND
HP CUT OUTS
Strong variations of
pressure ( 2 to 3
bar) Thermostatic
Expansion Valve
"hunting"
Very high discharge
temperature,
High amps
measured at
compressor
POSSIBLE CAUSE AND SYMPTOMS
Moisture or contaminants in the system
Condenser coil is obstructed
Recycled Hot Air
Incorrect adjustment of the expansion valve
Low refrigerant charge
Filter drier obstructed with gas bubbles at the
expansion valve inlet
Moisture in the system
Very high superheat, very hot compressor
Four Way reversing valve possibly blocked,
abnormal noise from the valve, low LP and
increasing HP
SOLUTION
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
Check the condenser coil and clean is
necessary
Check clearance around the condenser
Refer to LP problems and LP cut out section
Open the superheat adjustment on the expan-
sion valve.
Check the pressure drop on the filter drier in the
suction line
Check operation of the valve by going through
cycle inversions. Change if necessary.
Refer to LP problems
INDOOR FAN BLOWER
REFRIGERATION
FAULT
High amps on
action Fan motor
High amps on
reaction Fan motor
Unstable running
and high vibration
POSSIBLE CAUSE AND SYMPTOMS
Pressure drop in the ducting installation too low.
Pressure drop in the ducting installation too high.
Fan jumping from one operating point to
the other.
SOLUTION
Reduce the rotation speed of the fan
Measure and estimate the airflow and pressure
and compare with the specification from
customer.
Reduce the rotation speed of the fan
Measure and estimate the airflow and pressure
and compare with the specification from
customer.
Change rotation speed of the fan.
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