Toyota Tundra Service Manual: System Description

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.

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.

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.

FACE

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-

-

-

-

-

Mid1

-

-

-

-

B/L

-

-

-

-

Mid2

-

-

-

-

FOOT

Mid3

F/D

Mid4

DEF

-

-

-

-

-

-

FACE

-

-

-

-

-

-

-

-

Mid1

-

-

-

-

B/L

-

-

-

-

Mid2

-

-

-

-

FOOT

Mid3

F/D

Mid4

DEF

-

-

-

-

-

-

-

-

FACE

-

-

-

-

-

-

-

-

Mid1

-

-

-

-

B/L

-

-

-

-

Mid2

-

-

-

-

FOOT

Mid3

F/D

Mid4

DEF

-

-

-

-

-

-

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