Toyota Camry 1999 Electrical Troubleshooting Manual page 301

SYSTEM OUTLINE
Current always flows from the HTR fuse to TERMINAL 1 of the HTR relay. When the ignition SW is turned on, the current
from the HEATER fuse flows to TERMINAL 6 of the air vent mode control servo motor, to the MG CLT relay (Coil side) to
TERMINAL MGC of the A/C amplifier (1MZ–FE) or TERMINAL MGC of the engine control module (5S–FE), to TERMINAL 1
of the A/C dual pressure SW to TERMINAL 4 to TERMINAL +B of the A/C amplifier (1MZ–FE) or TERMINAL PRS of the
engine control module (5S–FE), current also to the HTR relay (Coil side) to TERMINAL 3 of the blower SW.
1. AIR VENT MODE CONTROL SERVO MOTOR OPERATION
When the damper is in FACE position and B/L mode on the heater control SW is selected, current flows from TERMINAL 7
of the heater control SW to TERMINAL 2 of the air vent mode control serve motor so that a signal that the ground circuit is
activated is input into TERMINAL B of the control circuit inside the air vent mode control servo motor. Simultaneously, a
signal that the ground circuit is not activated is input into TERMINAL A of the control circuit inside the servo motor. These two
signals activate the control circuit so that current flows from the HEATER fuse to the servo motor, causing the servo motor to
operate and the damper to move to B/L position. When the damper reaches B/L position. A ground cut signal is input into
TERMINAL B of the control circuit, the control circuit operates, the servo motor stops rotating and the damper stops at B/L.
When another mode position is selected, input of signals into TERMINAL A and TERMINAL B of the control circuit that
ground is made or not (as explained above) activates the control circuit and moves the serve motor to the desired position.
2. AIR CONDITIONING OPERATION
When the blower SW is on, current flows from the HEATER 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 2 of the A/C SW. If the A/C SW is turned on at this time, a signal is input into the A/C
amplifier (1MZ–FE) or engine control module (5S–FE). This activates the A/C amplifier (1MZ–FE) or engine control module
(5S–FE) and MG CLT relay so that current flows from the HEATER fuse to the MG CLT relay (Point side) to A/C magnetic
clutch. Causing The compressor to operate.
When blower SW is on and heater control SW is at DEF position, it causes A/C to run whether A/C SW is on or not.
SERVICE HINTS
HTR RELAY [R/B NO.1]
1–2 : Closed with the ignition SW on and the blower SW on
MG CLT RELAY [R/B NO.1]
5–3 : Closed with the ignition SW on, the blower SW on and the A/C SW on or the heater control SW at DEF position
A3 A/C DUAL PRESSURE SW
1–4 : Open with pressure 2.0 kgf/cm
B4 BLOWER RESISTOR
6–1 : Approx. 0.62 Ω
1–3 : Approx. 1.46 Ω
2–6 : Approx. 0.38 Ω
: PARTS LOCATION
Code See Page
26 (1MZ–FE)
A2 A2
28 (5S–FE)
26 (1MZ–FE)
A3 A3
28 (5S–FE)
A12 30
A13 30
A14 30
A20 30
B3 30
: RELAY BLOCKS
Code See Page
1 24
2
(29 psi, 196 kpa) or above 32 kgf/cm
Code
B4
B5
D3
E7 A
E8 B
E9 C
F8 F8
H9
Relay Blocks (Relay Block Location)
Engine Room R/B No.1 (Engine Compartment Left)
2
(464 psi, 3138 kpa)
See Page
30
30
26 (1MZ–FE)
30
30
30
26 (1MZ–FE)
28 (5S–FE)
30
Code See Page
J8 31
J11 31
J12 31
J23 31
J27 A 31
J28 B 31
J29 31
J32 31