Toyota Tundra 2005 Service - Repair - Maintenance page 3975

Air Conditioning (Access/Standard Cab)
System Outline
1. Heater Blower Motor Operation
Current is applied at all times through the HTR fuse to TERMINAL 5 of the HTR relay.
When the ignition SW is turned on, current flows through the GAUGE fuse to TERMINAL 2 of the HTR relay to the coil side
to TERMINAL 1 to TERMINAL 3 of the blower SW.
∗ Low speed operation
When the blower SW is moved to LO position, current flows to TERMINAL 3 of the blower SW to TERMINAL 1 to
GROUND, causing the HTR relay to switch on. This causes the current to flow from the HTR fuse to TERMINAL 5 of the
HTR relay to TERMINAL 3 to TERMINAL 1 of the blower motor to TERMINAL 2 to TERMINAL 4 of the blower resistor to
TERMINAL 1 to GROUND, causing the blower motor to rotate at low speed.
∗ Medium speed operation (Operation at M1, M2)
When the blower SW is moved to M1 position, current flows to TERMINAL 3 of the blower SW to TERMINAL 1 to
GROUND, turning the HTR relay to switch on. This causes the current to flow from the HTR fuse to TERMINAL 5 of the
HTR relay to TERMINAL 3 to TERMINAL 1 of the blower motor to TERMINAL 2 to TERMINAL 4 of the blower resistor to
TERMINAL 3 to TERMINAL 4 of the blower SW to TERMINAL 1 to GROUND. At this time, the blower resistance of the
blower resistor is less than at low speed, so the blower motor rotates at medium low speed.
When the blower SW is moved to M2 position, current flows through the motor flows from TERMINAL 4 of the blower
resistor to TERMINAL 2 to TERMINAL 8 of the blower SW to TERMINAL 1 to GROUND. At this time, resistance of the
blower resistor is less than at M1 position, so the blower motor rotates at medium high speed.
∗ High speed operation
When the blower SW is moved to HIGH position, current flows to TERMINAL 3 of the blower SW to TERMINAL 1 to
GROUND, turning the HTR relay to switch on.
This causes the current to flow from the HTR fuse to TERMINAL 5 of the HTR relay to TERMINAL 3 to TERMINAL 1 of the
blower motor to TERMINAL 2 to TERMINAL 5 of the blower SW to TERMINAL 1 to GROUND, causing the blower motor to
rotate at high speed.
2. Operation of Air Inlet Control Servo Motor
∗ Switching from FRESH to RECIRC
With the ignition SW turned on, current flows from the GAUGE fuse to TERMINAL 5 of the air inlet control servo motor.
When the RECIRC/FRESH SW is switched to the RECIRC side, current flows from TERMINAL 5 of the air inlet control
servo motor to TERMINAL 1 to TERMINAL (A) 8 of the integration control and panel to TERMINAL (B) 1 to GROUND. The
motor rotates and the damper moves to the RECIRC side. When it is in the RECIRC position, current is cut inside the
servo motor and the damper stops at that position.
∗ Switching from RECIRC to FRESH
With the ignition SW turned on, when the RECIRC/FRESH SW is switched to the FRESH side, current flows from
TERMINAL 5 of the air inlet control servo motor to TERMINAL 2 to TERMINAL (A) 7 of the integration control and panel to
TERMINAL (B) 1 to GROUND, the motor rotates and the damper moves to the FRESH side. when it is in the FRESH
position, current is cut inside the servo motor and the damper stops at that position. When the ignition SW turned on, and
mode SW (Integration control and panel) is at DEF or F/DEF position, it causes the damper to move to the FRESH side.
Whether the RECIRC/FRESH SW (Integration control and panel) is on or not.
3. Air Conditioning Operation
When the blower SW is on, current flows from the GAUGE fuse to the HTR relay (Coil side) to TERMINAL 3 of the blower
SW to TERMINAL 1 to GROUND, activating the HTR relay. This causes current to flow from the HTR fuse to the HTR relay
(Point side) to A/C fuse to TERMINAL (B) 12 of the A/C SW (Integration control and panel). When the A/C SW (Integration
Control and panel) is turned on. Current flows from the A/C fuse to TERMINAL (B) 14 of the integration control and panel to
TERMINAL (B) 18 to A/C magnetic clutch. Causing The compressor to operate.
When blower SW is on and mode SW (Integration control and panel) is at DEF or F/DEF position, it causes A/C to run
whether A/C SW (Integration control and panel) is on or not.
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2005 TOYOTA TUNDRA (EWD611U)