Mitsubishi Heavy Industries SRK25GZ-L1 Handbook page 356

FDT ( N ) -H
4
Abnormality casued by insufficient refrigerant.
Indoor unit
Check Lamp (yellow)
Note (1) Refer to previous page for heat exchanger thermistor tempera-
ture resistance characteristic values.
5
Heating overload
Indoor unit
Check Lamp (yellow)
Is the air filter
clogged?
NO
Is the indoor
unit heat exchanger
thermistor connector
connection OK?
NO
Correction
(ii) Only case of wired remote control model
1 e 1
Error display :
Is there
DC 10.8V
between control
YES
switch circuit board con-
nector (CnB) X
(Red) to Z
(Black)?
NO
Is there
DC 10.8V
YES
between indoor unit
PCB connector (CNB)
1 (Red) to 3
(Black)?
NO
The control switch wiring (red)
Defective indoor or (black) is broken or have a
unit PCB defective connection.
354
5 time flashes
6 time flashes
YES
Washing
Are the heat
YES
exchanger thermistor
characteristics OK, is
there no short
circuit?
NO
Defective heat exchanger
thermistor Replacement
[Communication error between control switch ~ Indoor unit PCB]
Does the
voltage oscillate
between DC6 and 10V
YES
between control switch
circuit board connector
(CnB) Y (White)
to Z (Black)?
NO
Defective control
switch PCB
Are the
NO
characteristic values for
the heat exchanger
thermistor OK?
YES
Is the
amount of refrigerant
NO
circulation good? (If refrige-
rant is insufficient, the ca-
pillary tubes may be
plugged.)
YES
Printed circuit board for indoor
unit no good replace.
Note (1) To see whether or not it is over-
loaded, check the following:
uIs the inside/outside air tem-
(
perature too high?
uIs there any short circuit?
uIs the refrigerant excessive?
YES
Is the heating
under overload?
Defective indoor unit PCB
Replacement (Defective indoor unit heat
exchanger thermistor input circuit)
• Normal voltage for control switch wiring (DC)
Between X and Z : 10.5 ~ 10.8 V
Between Y and Z : 5 ~ 10.8 V
Does the
voltage oscillate
between DC6 and
YES
10V between indoor unit
PCB connector (CNB)
2 (White) to 3
(Black)?
NO
The control switch wiring
(white) or (black) is broken or
have a defective connection.
Note (1) If it is normalized by changing PCB, judge the control switch or indoor
unit PCB (Communication error between control switch and unit) is
detective.
Replace heat exchanger thermistor.
Charge with refrigerant.
Replace capillary tubes.
)
(1)
YES
Adjustment
NO
Unit is normal
(Intrusion of accidental
noise on the control switch
cord)
YES
Power
Is it
supply
normalized?
reset
NO
Defective control switch
PCB Replacement
Defective indoor unit PCB
Replacement
(1)