Inspection Procedure For The Electronic Controller - Daikin LXE10E-A Service Manual

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3.7 Inspection procedure for the electronic controller

DECOS 3c enables the internal data of the controller CPU (RAM data) to be displayed on the monitor of a
personal computer by connecting the two with a communication cable. This makes it possible to preform an
easy inspection of the controller and diagnose any defect.
(1) Inspection of sensors
The inspection is carried out by comparing the sensor readings on the controller display with the
display on the personal computer. In case the sensor reading is abnormal, the sensor should be
replaced with a new one, but be sure to check the sensor for damage as well as the internal
harness and its connectors before replacing. (Refer to Appendix for the sensor characteristics.)
Page 7-3 and 7-4.
(2) Inspection of the internal relays of the electronic controller
The inspection is carried out by checking the display on the personal computer and the internal
relay output (24VAC) on the terminals of terminal board, utilizing the electric tester or test lamp. In
case the internal relay malfunctions, the power I/O board should be replaced with a new one, but
be sure to check the internal harness and its connectors for damage before replacing.
(3) Inspection of the Suction modulation valve
Suction modulation valve is driven by the PCB adapter. If the Suction modulation valve does not
function (i.e. if there is no clicking sound, ever though the control display shows the valve openning and
closing), then the PCB adapter should be replaced, but be sure to check the internal harness and its
connectors for damage before replacing.
(4) Inspection of the electronic expansion valve
If the electronic expansion valve does not operate (no clicking sound) when the valve opening is
changed on the controller indication, the electronic expansion valve should be replaced. However,
check on damage of internal harness and poor contact of connector before the replacement.
(5) Inspection of the cpu board
If the green light on the cpu board is flashing, then the cpu board is working normally.
●Basic internal wiring diagram of electronic controller
CPU board
A/D
converter
CN18
CN17
EV
PT/CT
board
BAT
CN14
CPU
Relay
driver
CN
20
CN13
CN16
CN
19
MV
driver
Display
board
Sheet key
Power I/O board
External output
and WPS/HPS/CTP
input
PHC
TB1
Relay
CN25 CN21
Adopter board
CN82
CN83 CN84
SMV
TrC
3-42
Sensor input
CN2
CN7
CN1 CN6
CN3
CN5
TES3
CN4
MV
CN81