381
Troubleshooting
Alarm code
A4
Auxiliary sensor Abnormality (Tow2)
● Alarm code is displayed on the master controller/ the 7-segment of O.U. display PCB / the 7-segment of I.U. PCB1.
● This alarm code is indicated when a short circuit (less than 0.24kΩ) or disconnection (more than 840kΩ) of the thermistor
is detected during the heating or cooling operation. The operation is automatically restarted when the malfunction is
removed.
● Reset the unit to release the alarm.
0
10
20
30
40
50
60
70
80
82
61
46
35
27
20.5
16
12.5
10
8
5.3
3.6
2.5
90
Thermistor
Resistance
(kΩ)
-15 -10 -5 0 5 10 15 20 25 30 35 40 45 50 55 60
Ambient Temperature (
o
C)
Thermistor Characteristics
*I.U. PCB4 connected to corresponding
sensor port on I.U.PCB1
I.U. PCN4 I.U.PCN4 I.U.PCB1
A1
CN1-12
THM8
CN1-11
A2
CN1-8
THM10
CN1-7
A3
CN1-10
THM9
CN1-9
A4
CN2-10
THM6
CN2-9
A5
CN1-6
THM11
CN1-5
A6
CN1-4
THM17
CN1-3
A7
CN1-2
THM18
CN1-1
No
ow2
Yes
Yes
No
Is Cycle 2 is set
enabled on Master
Controller?
The thermistor
connected to A1-A7 on
PCB4 must be the
same as set Auxiliary
Sensor A1-A7 in
Master Controller
interface
thermistor connected
Faulty I.U. PCB1 or
I.U. PCB4
(Check PCBs)
No
Yes
Yes
No
Yes
No
Set Tow2 on any of
Auxiliary Sensor A1-A7
in Master Controller
Tow2 set on
Auxiliary Sensor A1-A7
in Master
Controller?
on I.U.PCB1*
connected to
on I.U.PCB4 as
To Next Page
