Johnson Controls CICM008B21S, Service Manual

Page: 46 / 152

3-24
SM-18003
TROUBLESHOOTING
Alarm
Code
Abnormality of Thermistor for Indoor Unit Inlet Air Temperature
(Inlet Air Thermistor)
NOTICE:
This figure is applicable to the following thermistors.
1. Inlet Air Thermistor (THM1), 2. Liquid Pipe Thermistor (Freeze Protection) (THM3), 3. Gas Pipe Thermistor (THM5),
4. Outlet Air Thermistor (THM2), 5. Outside Air Thermistor or Remote Thermistor (THM4)
l
The RUN indicator (red) flashes.
l
The indoor unit number (refrigerant cycle number - address number), the alarm code, the model code
1
,
the model name
1
and the number of connected indoor units are displayed on the LCD. The indoor unit
number and the alarm code are displayed on the 7-segment display of the outdoor unit PCB.
Note 1: Except for some models.
This alarm code is displayed when a short (0.24kΩ or less) or open sensor (840kΩ or more) is detected
during a heating or cooling operation. The operation automatically restarts when the malfunction is
removed.
Yes
Yes
Connect them.
No
Failure of
Thermistor
Failure of I.U. PCB
No
Is thermistor THM1
(for inlet air temp.)
connected to THM1
of I.U. PCB?
Is resistance of THM1
between 0.24k Ω and
840k Ω ?
Cause Check Item
Action
(Turn OFF Main Switch)
Event
Failure of
Inlet Air
Thermistor
Check resistance.
Replace thermistor
if faulty.
Failure
Check connection.
Correctly connect wires.
Incorrect Connection
Replace I.U. PCB
and check operation.
Replace I.U. PCB
if faulty.
Failure of I.U. PCB
0
10
20
30
40
50
60
70
80
(-15) (-10) (-5) (0) (5) (10) (15) (20) (25) (30) (35) (40) (45) (50) (55) (60)
82
61
46
35
27
20.5
16
12.5
10
8
5.3
3.6
2.5
90
Thermistor
Resistance
(kΩ)
Thermistor Characteristics
5 14 23 32 41 50 59 68 77 86 95 104 113 122 131 140
Ambient Temperature ( o F( o C))
Indication on Outdoor Unit PCB
(Alarm Code 11 ~ 19)
Unit No. of
Malfunctioning Indoor Unit
Alarm Code
(11 ~ 19)
Inlet Air Thermistor