Dtc B1520 (No.20): Temperature Selector And/Or Its Circuit Malfunction; Dtc B1521 (No.21): Blower Speed Selector And/Or Its Circuit; Dtc B1522 (No.22): Air Flow Selector And/Or Its Circuit Malfunction; Inspection Of Hvac Control Module And Its Circuit - Suzuki Liana RH413 Service Manual

7B-67 Air Conditioning System: Automatic Type
Step
6 1) Check air flow control actuator referring to "Air Flow
Control Actuator Inspection in Section 7A".
Is air flow control actuator normal?
DTC B1520 (No.20): Temperature Selector and/
or its Circuit malfunction
DTC Detecting Condition
This DTC will be set when an internal fault is detected in
HVAC control module.
DTC Troubleshooting
Replace HVAC control module with new one referring to
"HVAC Control Module Removal and Installation in
Section 7A".
DTC B1521 (No.21): Blower Speed Selector and/
or Its Circuit
DTC Detecting Condition
This DTC will be set when an internal fault is detected in
HVAC control module.

Inspection of HVAC Control Module and its Circuit

HVAC control module and its circuits can be checked at HVAC control module wiring couplers by measuring voltage.
CAUTION
!
HVAC control module can not be checked by itself. It is strictly prohibited to connect voltmeter to
HVAC control module with couplers disconnected from it.
Voltage Check
1) Remove HVAC control module referring to "HVAC Control Module Removal and Installation in Section 7A".
2) Check voltage at each terminal.
NOTE
As each terminal voltage is affected by the battery voltage, confirm that it is 11 V or more when ignition
switch is ON.
1
1. HVAC control module
Terminal Wire Color
G77-1 GRN/WHT A/C signal
Action
S3RH0A7224020
S3RH0A7224021
14
30
2. HVAC control module connector "G77" (viewed from harness side)
Normal
Circuit
Voltage
6.0 – 14.0 V A/C switch OFF
0 – 1.5 V
Yes
HVAC control module
faulty.
DTC Troubleshooting
Replace HVAC control module with new one referring to
"HVAC Control Module Removal and Installation in
Section 7A".
DTC B1522 (No.22): Air Flow Selector and/or its
Circuit Malfunction
DTC Detecting Condition
This DTC will be set when an internal fault is detected in
HVAC control module.
DTC Troubleshooting
Replace HVAC control module with new one referring to
"HVAC Control Module Removal and Installation in
Section 7A".
2
13 12 11 10 9 8
29 28 27 26 25 24 23 22 21 20 19 18 17 16 15
A/C switch ON
No
Air flow control actuator
faulty.
S3RH0A7224022
S3RH0A7224023
7 6 5 4 3 2 1
I3RH0A722017-01
Condition