57
LOW PRESSURE SHUTDOWN - COOLING
LOW PRESSURE SHUTDOWN
Indoor unit working
correctly?
Check operation
of the indoor unit ( 1 )
Dewatering filter
working efficiently?
Refrigerant charge
correct?
Intake valve completely
open?
Intake temperature and/or
pressure correct?
Unit working
Check operating conditions
of the indoor unit ( 2 )
Check connection pipes
( 3 )
Control
subcooling/subheating (5)
Check and open if
necessary
Check operation
of outdoor unit ( 6 )
Check
∆
t from upstream
to downstream ( 4 )
NO
NO
NO
NO
YES
YES
YES
YES
NO
Notes
1) Check:
- That there is sufficient air flow.
- That the direction of rotation of the fans is correct.
- That the exchanger is not dirty or blocked, and can provide maximum heat exchange.
- That the solenoid valve is working.
- That the thermostat is working.
2) Check that the temperature/humidity conditions of the air being treated falls within the design conditions.
3) Check that the layout and the diameter of the pipes are correctly sized (see the section on REFRIGERANT PIPES). If not,
unacceptable pressure drops may occur for the correct operation of the unit.
4) Check, using a thermometer in direct contact, the temperature upstream and downstream of the dewatering filter. If the
difference in temperature is higher than 1°C, the filter is not working efficiently or is under-rated; in both cases, replace the
filter.
5) For information on how to perform the checks, please refer to section on START-UP.
6) If the condensing pressure is below 1200kPa there may be irregular supply to the expansion device and as a consequence
too low inlet pressure.
Check that the ventilation system for the outdoor unit is working perfectly (that is, modulates or stops the fans).
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