Toyota Tundra Service Manual: System Description

SYSTEM DESCRIPTION

1. GENERAL

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

Control

Outline

Manual Control

The air conditioning amplifier controls the damper positions (air inlet control damper, air mix control damper and mode control damper) and blower speed in accordance with the positions of the switches (temperature control switch, blower switch, mode select switch and air inlet control switch).

MAX A/C Control

When the temperature control switch is in the MAX A/C position, the air conditioning amplifier turns the compressor on and activates the servo motor (air inlet) to set the air inlet control damper to the RECIRC position, improving the cooling efficiency.

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.

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 Regular Cab and 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.

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.

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 Regular Cab)

(a) Air Outlets and Airflow Volume

INDICATION

(MODE)

FACE

FOOT

DEF

CENTER

SIDE

FRONT

CENTER

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

K

J

L

I

FACE

-

-

-

-

-

-

Mid1

-

-

-

-

B/L

-

-

-

-

Mid2

-

-

-

-

FOOT

Mid3

F/D

Mid4

DEF

-

-

-

-

-

-

5. 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

FACE

-

-

-

-

-

-

-

-

Mid1

-

-

-

-

B/L

-

-

-

-

Mid2

-

-

-

-

FOOT

Mid3

F/D

Mid4

DEF

-

-

-

-

-

-

-

-

6. 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

FACE

-

-

-

-

-

-

-

-

Mid1

-

-

-

-

B/L

-

-

-

-

Mid2

-

-

-

-

FOOT

Mid3

F/D

Mid4

DEF

-

-

-

-

-

-

-

-

-

    Problem Symptoms Table

    System Diagram

    See More:

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