Daikin GYEQ20AN Service Manual page 149

SiAUY361411EA
8
Abnormal Low-Side Pressure
Description Sub-code 0: While the unit is running, the low-side pressure drops to 0.05 MPa or lower.
of the failure
Sensor failure; refrigerant level too low; EV failure; SV failure; piping clogged;
Possible
causes outdoor heat exchanger clogged; indoor heat exchanger clogged; fan failure; thermostat failure;
of the failure
stop valve failure; cooling water pump failure; cooling water pump concentration too low; external filter clogged
Flow chart
Are Indoor Unit Filters
And Heat Exchanger
Free From Clogging?
YES
Are Fans Operating Normally?
YES
Are Stop Valves Opened?
YES
Are EVs Operating Normally?
YES
Is Refrigerant Amount Sufficient?
YES
Are Pressure Sensors
Operating Normally?
YES
Are Intake Air Temperature
Sensors Operating Normally?
YES
Is SV1, SV3E, and SV3F
operating normally?
YES
Is Cooling Water Pump
Operating Normally?
YES
Is the thermostat
operating normally?
Is the water motor valve
operating normally?
YES
Is the piping and BS unit
free from clogging?
YES
Is Cooling water Concentration
Normal?
YES
Check the external filter.
Troubleshooting
Or the low-side pressure remains equal to or lower than 0.12 MPa for 20 seconds.
NO
Check Clogging.
NO
NO
Check Stop Valves.
NO
NO
Check Refrigerant Amount.
NO
Check Pressure Sensors.
NO
Check Intake Air
Temperature Sensors.
NO
Check SV1, SV3E and SV3F.
NO
Check Cooling Water Pump.
NO
Replace thermostat components
Replace water motor valve
NO
See Refrigerant
System Diagram.
NO
Check Cooling Water
Check Fans.
Check EVs.
Concentration.
025871-00EN04
Flow Charts for Troubleshooting
Error
code
E9
138