Heating / Air Conditioning

Air Conditioning Control Panel Circuit

~2min read
DESCRIPTION

This circuit consists of the air conditioning control assembly and the A/C amplifier. When the air conditioning control assembly is operated, signals are transmitted to the A/C amplifier through the LIN communication system.

If the LIN communication system malfunctions, the A/C amplifier does not operate even if the air conditioning control assembly is operated.

WIRING DIAGRAM
CAUTION / NOTICE / HINT

NOTICE:

Inspect the fuses for circuits related to this system before performing the following inspection procedure.

PROCEDURE
  1. CHECK HARNESS AND CONNECTOR (AIR CONDITIONING CONTROL ASSEMBLY - BODY GROUND)

(a) Disconnect the air conditioning control assembly connector.


(b) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

Tester Connection

Condition

Specified Condition

E3-5 (GND) - Body ground

Always

Below 1 Ω

Text in Illustration

*1

Front view of wire harness connector

(to Air Conditioning Control Assembly)


NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK
  1. CHECK HARNESS AND CONNECTOR (AIR CONDITIONING CONTROL ASSEMBLY - BATTERY)

(a) Measure the voltage according to the value(s) in the table below.

Standard Voltage:

Tester Connection

Condition

Specified Condition

E3-4 (IG+) - E3-5 (GND)

Ignition switch ON

11 to 14 V

Text in Illustration

*1

Front view of wire harness connector

(to Air Conditioning Control Assembly)


NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK
  1. CHECK HARNESS AND CONNECTOR (A/C AMPLIFIER - AIR CONDITIONING CONTROL ASSEMBLY)

(a) Disconnect the A/C amplifier connector.

(b) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

Tester Connection

Condition

Specified Condition

D47-37 (LIN1) - E3-2 (LIN1)

Always

Below 1 Ω

D47-37 (LIN1) - Body ground

Always

10 kΩ or higher

Text in Illustration

*1

Front view of wire harness connector

(to A/C Amplifier)

*2

Front view of wire harness connector

(to Air Conditioning Control Assembly)


NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK
  1. INSPECT AIR CONDITIONING CONTROL ASSEMBLY

(a) Replace the air conditioning control assembly (See page ).


HINT:

Since the air conditioning control assembly cannot be inspected while it is removed from the vehicle, replace the air conditioning control assembly with a new or a known good one and check that the condition returns to normal.

(b) Operate the air conditioning control assembly to check that it functions properly.

Result

Proceed to

Air conditioning control assembly malfunctions

A

Air Conditioning control assembly functions properly

B


A

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE


B

REPLACE AIR CONDITIONING CONTROL ASSEMBLY

Test yourself

A quick Toyota Venza quiz: every answer comes with an explanation and a link to the manual page.