Daikin FCQ18PVJU Service Manual page 112

Troubleshooting by Indication on the Remote Controller
Troubleshooting
105
Be sure to turn off the power switch before connecting or disconnecting
Caution
the connector, or parts could be damaged.
Is the stop
valve open?
Mount a pressure gauge on the low-pressure service port.
Connect the Service Checker.
Reset the operation using the remote controller, and then
restart the operation.
Are the
characteristics of the
low pressure sensor
normal?
(See *1.)
Is the
pressure detected
with the P.C.B.
normal?
(See *2.)
· The low pressure sensor is normal, and the pressure
detected with the P.C.B. is also normal.
· The low pressure has really become low.
(Refer to P.157)
CHECK 2
Remove the causes by which the low pressure has become low.
*1: Make a comparison between the voltage of the pressure sensor and that read by the
pressure gauge.
(As to the voltage of the pressure sensor, make measurement of voltage at the connector,
and then convert it to pressure according to information on P.168.)
*2: Make a comparison between the low pressure value checked with the Service Checker
and the voltage of the pressure sensor (see *1).
*3:Take measurement of voltage of the pressure sensor.
Micro controller
A/D input
Take measurement of DC voltage between these wires.
NO
YES
NO
YES
NO
YES
+5V
Connector for low pressure sensor
(Blue)
(4)
(3)
(2)
(1)
SiUS28-902_a
Open the stop valve.
Replace the low pressure sensor.
Replace the main P.C.B..
Red
Black
Low
pressure
White sensor
Troubleshooting