Mitsubishi Electric EHST20C-VM6HB Service Manual page 34

Check Code Abnormal point and detection method
Compressor overcurrent interruption
Abnormal if overcurrent DC bus or
compressor is detected after compressor
starts operating for 30 seconds.
UP
Remote controller transmission error (E0)/
signal receiving error (E4)
1 Abnormal if main or sub remote
controller cannot receive normally
any transmission from indoor unit of
refrigerant address "0" for 3 minutes.
(Check code : E0)
2 Abnormal if sub remote controller could
not receive any signal for 2 minutes.
(Check code: E0)
1 Abnormal if indoor controller board
cannot receive normally any data from
remote controller board or from other
E0
indoor controller board for 3 minutes.
or
(Check code: E4)
E4
2 Indoor controller board cannot receive
any signal from remote controller for 2
minutes. (Check code: E4)
Remote controller control board
1 Abnormal if data cannot be normally
read from the nonvolatile memory of the
remote controller control board.
(Check code: E1)
E1
2 Abnormal if the clock function of remote
or
controller cannot be normally operated.
E2
(Check code: E2)
OCH533D
Case
1 Stop valve of outdoor unit is
closed.
2 Decrease of power supply
voltage
3 Looseness, disconnection or
converse of compressor wiring
connection
4 Defective fan of outdoor units
5 Short cycle of outdoor units
6 Defective input circuit of
outdoor controller board
7 Defective compressor
8 Defective outdoor power circuit
board
9 Dip switch setting difference of
outdoor controller circuit board
1 Contact failure at transmission
wire of remote controller
2 All remote controllers are set
as "sub" remote controller.
In this case, E0 is displayed
on remote controller, and E4
is displayed at LED (LED1,
LED2) on the outdoor controller
circuit board.
3 Miswiring of remote controller
4 Defective transmitting receiving
circuit of remote controller
5 Defective transmitting receiving
circuit of indoor controller board
of refrigerant address "0"
6 Noise has entered into the
transmission wire of remote
controller.
1 Defective remote controller
34
Judgment and action
1 Open stop valve.
2 Check facility of power supply.
3 Correct the wiring (U V W phase) to
• •
compressor. Refer to "11-6. TEST POINT
DIAGRAM" (Outdoor power circuit board).
4 Check outdoor fan.
5 Solve short cycle.
6 Replace outdoor controller circuit board.
Note: Before the replacement of the outdoor
controller circuit board, disconnect the
wiring to compressor from the outdoor
power circuit board and check the output
voltage among phases, U, V, W, during
test run.
No defect on board if voltage among
phases (U-V, V-W and W-U) is same.
Make sure to perform the voltage check
with same performing frequency.
7 Check compressor. Refer to "11-4. HOW TO
CHECK THE PARTS".
8 Replace outdoor power circuit board.
9 Check the DIP switch setting of outdoor
controller circuit board.
1 Check disconnection or looseness of indoor
unit or transmission wire of remote controller.
2 Set one of the remote controllers "main" if
there is no problem with the action above.
3 Check wiring of remote controller.
Refer to the indoor unit's Installation Manual
for remote controller connection.
If the cause of trouble is not in above 1–3,
4 Diagnose remote controllers.
a) When "RC OK" is displayed,
Remote controllers have no problem.
Turn the power off, and on again to check.
If abnormality generates again, replace
indoor controller board.
b) When "RC NG" is displayed,
Replace remote controller.
c) When "RCE3" or "ERC00-66" is displayed,
noise may be causing abnormality.
Note: If the unit is not normal after replacing
indoor controller board in group control,
indoor controller board of address "0"
may be abnormal.
1 Replace remote controller.