Toyota Tundra Service Manual: System Description

SYSTEM DESCRIPTION

1. GENERAL

(a) The air conditioning system has the following controls:

Control

Outline

Outlet Air Temperature Control

Based on the temperature set by the temperature control switch, the neural network control calculates the outlet air temperature based on the input signals from various sensors.

The temperature setting for the driver and front passenger are controlled independently in order to provide different vehicle interior temperatures for the right and left side of the cabin. As a result, the air conditioning system accommodates the occupants' preferences.

Blower Control

Controls the blower motor in accordance with the airflow volume that has been calculated by the neural network control based on the input signals from various sensors.

Air Outlet Control

Automatically switches the air outlets in accordance with the outlet mode that has been calculated by the neural network control based on the input signals from various sensors.

In accordance with the engine coolant temperature, outside air temperature, amount of sunlight, required blower, outlet temperature, and vehicle speed conditions, this control automatically switches the blower outlet to the FOOT / DEF mode to prevent the windows from becoming fogged when the outside air temperature is low.

Air Inlet Control

Automatically controls the air inlet control damper to achieve the calculated required outlet air temperature.

Drives the servo motor (for air inlet) according to the operation of the air inlet control switch and moves the dampers to the FRESH or RECIRC position.

Compressor Control

Through the calculation of the target evaporator temperature based on various sensor signals, the air conditioning amplifier optimally controls the discharge capacity by regulating the opening extent of the air conditioning compressor solenoid valve.

The air conditioning amplifier compares the pulley speed signals, which are transmitted by the lock sensor located on the air conditioning compressor, with the engine speed signals, which are transmitted by the ECM (crankshaft position sensor). When the air conditioning amplifier determines that the pulley is locked, it turns off the magnetic clutch.

Neural Network Control

This control is capable of effecting complex control by artificially simulating the information processing method of the nervous system of living organisms in order to establish a complex input / output relationship that is similar to a human brain.

Self-Diagnosis

A DTC (Diagnostic Trouble Code) is stored in the memory when the air conditioning amplifier detects a problem with the air conditioning system.

2. MODE POSITION AND DAMPER OPERATION (for Double Cab)

(a) Mode Position and Damper Operation

Functions of Main Dampers:

Control Damper

Operation Position

Damper Position

Operation

Air Inlet Control Damper

FRESH

B

Brings in fresh air.

RECIRC

A

Recirculates internal air.

Air Mix Control Damper

MAX COLD to MAX HOT Temperature Setting

C - E

F - H

I - K

Varies the mixture ratio of fresh air and recirculated air in order to regulate the temperature continuously from HOT to COLD.

Cool Air Bypass Damper

MAX COLD to MAX HOT Temperature Setting

U, V

Cool air blows out of the front center register and side registers in order to adjust the temperature around the head of the occupant during cooling or warming.

Air Outlet Control Damper

FACE

O, P, T, W

Air blows out of the front center register, side registers, and footwell ducts.*1

BI-LEVEL

M, P', S, W

Air mainly blows out of the front center register, side register, and footwell ducts.

FOOT

M, Q, R', X

Air mainly blows out of the front and rear footwell ducts. In addition, air blows out slightly from the front and side defrosters, front center register, and side register.*2

FOOT / DEF

M, P', R', Y'

Air mainly blows out of the front and side defrosters to defrost the windshield; air also blows out from the front and rear footwell ducts, front center register, and side register.*2

DEF

O, P, R, Y

Air blows out of the front and side defrosters and side registers to defrost the windshield.

HINT:

*1: In multi mode, air blows out of all the air outlets except the front and side defrosters.

*2: In multi mode, air blows out of all the air outlets.

3. MODE POSITION AND DAMPER OPERATION (for CrewMax)

(a) Mode Position and Damper Operation

Functions of Main Dampers:

Control Damper

Operation Position

Damper Position

Operation

Air Inlet Control Damper

FRESH

B

Brings in fresh air.

RECIRC

A

Recirculates internal air.

Air Mix Control Damper

MAX COLD to MAX HOT Temperature Setting

C - E

F - H

I - K

Varies the mixture ratio of fresh air and recirculated air in order to regulate the temperature continuously from HOT to COLD.

Cool Air Bypass Damper

MAX COLD to MAX HOT Temperature Setting

U, V

Cool air blows out of the front center register and side registers in order to adjust the temperature around the head of the occupant during cooling or warming.

Air Outlet Control Damper

FACE

O, P, T, W

Air blows out of the front center register, side registers, and footwell ducts.*1

BI-LEVEL

M, P', S, W

Air mainly blows out of the front center register, side register, and footwell ducts.

FOOT

M, Q, R', X

Air mainly blows out of the front and rear footwell ducts. In addition, air blows out slightly from the front and side defrosters, front center register, and side register.*2

FOOT / DEF

M, P', R', Y'

Air mainly blows out of the front and side defrosters to defrost the windshield; air also blows out from the front and rear footwell ducts, front center register, and side register.*2

DEF

N, P, R, Y

Air blows out of the front and side defrosters and side registers to defrost the windshield.

HINT:

*1: In multi mode, air blows out of all the air outlets except the front and side defrosters.

*2: In multi mode, air blows out of all the air outlets.

4. AIR OUTLETS AND AIRFLOW VOLUME (for Double Cab)

(a) Air Outlets and Airflow Volume

INDICATION

(MODE)

FACE

FOOT

DEF

CENTER

SIDE

FRONT

REAR

CENTER

SIDE

Driver Side

Passenger Side

Driver Side

Passenger Side

Driver Side

Passenger Side

Driver Side

Passenger Side

Driver Side

Passenger Side

Driver Side

Passenger Side

C

B

D

A

G

E

H

F

K

J

L

I

FACE1

-

-

-

-

-

-

-

-

FACE2

-

-

-

-

B/L

-

-

-

-

FOOT-D

FOOT-R

FOOT-F

F/D

DEF

-

-

-

-

-

-

-

-

5. AIR OUTLETS AND AIRFLOW VOLUME (for CrewMax)

(a) Air Outlets and Airflow Volume

INDICATION

(MODE)

FACE

FOOT

DEF

CENTER

SIDE

REAR

FRONT

REAR

CENTER

SIDE

Driver Side

Passenger Side

Driver Side

Passenger Side

-

Driver Side

Passenger Side

Driver Side

Passenger Side

Driver Side

Passenger Side

Driver Side

Passenger Side

C

B

D

A

M

G

E

H

F

K

J

L

I

FACE1

-

-

-

-

-

-

-

-

FACE2

-

-

-

-

B/L

-

-

-

-

FOOT-D

FOOT-R

FOOT-F

F/D

DEF

-

-

-

-

-

-

-

-

-

    Problem Symptoms Table

    System Diagram

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