Toyota Yaris: Air Conditioning System / A/C Switch Indicator does not Turn On

Toyota Yaris XP210 (2020-2024) Reapir and Service Manual / Vehicle Interior / Heating / Air Conditioning / Air Conditioning System / A/C Switch Indicator does not Turn On

DESCRIPTION

If none of the switch indicators on the air conditioning control assembly illuminate, the following factors may be the cause.

Symptom	Factor
A/C switch indicator does not illuminate	Vehicle control history (RoB) Air conditioning amplifier assembly malfunction Air conditioning control assembly malfunction A/C switch malfunction A/C switch indicator malfunction (including when indicator turned off without switch operation) Servo motor initialization (incomplete) Mechanical locking of damper and damper link Refrigerant pressure is extremely low Low detected ambient temperature (including thermistor assembly malfunction)

Symptom

Factor

A/C switch indicator does not illuminate

Vehicle control history (RoB)
Air conditioning amplifier assembly malfunction
Air conditioning control assembly malfunction
A/C switch malfunction
A/C switch indicator malfunction (including when indicator turned off without switch operation)
Servo motor initialization (incomplete)
Mechanical locking of damper and damper link
Refrigerant pressure is extremely low
Low detected ambient temperature (including thermistor assembly malfunction)

PROCEDURE

1.	CHECK MALFUNCTION STATUS

(a) Check the malfunction status of switch indicators on the air conditioning control assembly.

Result	Proceed to
Indicators are not always illuminated	A
Indicators are not illuminated only immediately after starting the engine	B

GO TO INITIALIZATION

2.	CHECK VEHICLE CONTROL HISTORY (RoB)

(a) Check vehicle control history according to the display on the GTS.

Body Electrical > Air Conditioner > Utility

Tester Display
Vehicle Control History (RoB)

(b) Record the vehicle control history.

Result	Proceed to
Vehicle control history is not output	A
Vehicle control history is output	B

GO TO VEHICLE CONTROL HISTORY (RoB)

3.	READ VALUE USING GTS (ROOM TEMPERATURE SENSOR)

(a) Read the Data List according to the display on the GTS.

Body Electrical > Air Conditioner > Data List

Tester Display	Measurement Item	Range	Normal Condition	Diagnostic Note
Room Temperature Sensor	Cooler (room temp. sensor) thermistor	Min.: -327.68°C(-557.82°F) Max.: 327.67°C(621.81°F)	Actual cabin temperature displayed	Cooler (room temp. sensor) thermistor circuit malfunction

Tester Display

Measurement Item

Range

Normal Condition

Diagnostic Note

Room Temperature Sensor

Cooler (room temp. sensor) thermistor

Min.: -327.68°C(-557.82°F)

Max.: 327.67°C(621.81°F)

Actual cabin temperature displayed

Cooler (room temp. sensor) thermistor circuit malfunction

Body Electrical > Air Conditioner > Data List

Tester Display
Room Temperature Sensor

OK:

The value displayed is 0°C (32°F) or higher.

INSPECT REFRIGERANT PRESSURE WITH MANIFOLD GAUGE SET

GO TO OTHER DIAGNOSIS PROCEDURE (Ambient Temperature Display System)

Ambient Temperature Display System

DESCRIPTION The thermistor assembly is installed in front of the cooler condenser assembly to detect the ambient temperature, which is used to control the automatic air conditioning system...

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