Toyota MR2 2000 Manual page 139

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, the current flows through HTR fuse to TERMINAL 1 of the HTR relay to TERMINAL 2 to
TERMINAL 8 of the blower SW.
∗ Low speed operation
When the blower SW is moved to LO position, the current flows the to TERMINAL 8 of the blower SW to TERMINAL 1 to
GROUND, causing the HTR relay to turn 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 1 of the blower resistor to
TERMINAL 4 to GROUND, rotating the blower motor at low speed.
∗ Medium speed operation (Operation at M1, M2)
When the blower SW is moved to M1 position, the current flows to TERMINAL 8 of the blower SW to TERMINAL 1 to
GROUND, causing the HTR relay to turn on. This causes the current flows 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 1 of the blower resistor to
TERMINAL 2 to TERMINAL 6 of the blower SW to TERMINAL 1 to GROUND. At this time, the blower resistance of the
blower resistor is smaller than at low speed, so the blower motor rotates at medium low speed.
When the blower SW is moved to M2 position, the current through the motor flows from TERMINAL 1 of the blower
resistor to TERMINAL 3 to TERMINAL 5 of the blower SW to TERMINAL 1 to GROUND. At this time, resistance of the
blower resistor is smaller than at M1 position, so the blower motor rotates at medium high speed.
∗ High speed operation
When the blower SW is moved to HI position, the current flows to TERMINAL 8 of the blower SW to TERMINAL 1 to
GROUND, causing the HTR relay to turn on.
This causes the current to flow from the HTR fuse to TERMINAL 5 of the heater relay to TERMINAL 3 to TERMINAL 1 of
the blower motor to TERMINAL 2 to TERMINAL 3 of the blower SW to TERMINAL 1 to GROUND, rotating the blower
motor at high speed.
SERVICE HINTS
HTR RELAY
3–5 : Closed with the ignition SW at ON position and the blower SW on
A11 A/C DUAL PRESSURE SW
1–4 : Open with the refrigerant pressure at less than approx. 196 Kpa (2.0 kgf/cm
approx. 3140 Kpa (32 kgf/cm
: PARTS LOCATION
Code See Page
A1 30
A4 32
A5 32
A11 34
: RELAY BLOCKS
Code See Page
1 22
2 23
3 24
: JUNCTION BLOCK AND WIRE HARNESS CONNECTOR
Code See Page
6B
26 26
6E
2
, 455 psi)
Code
B2
B3
B4
C10 A
Relay Blocks (Relay Block Location)
Fusible Link Block (Engine Compartment Left)
Engine Room R/B (Left Side of Room Partition Panel)
R/B No.3 (Left Side of Instrument Panel)
Junction Block and Wire Harness (Connector Location)
Instrument Panel Wire and J/B No.6 (Instrument Panel Brace LH) Instrument Panel Wire and J/B No 6 (Instrument Panel Brace LH)
See Page
32
32
32
32
2000 MR2 (EWD408U)
2
, 28.4 psi) or more than
Code See Page
C11 B 32
C12 C 32
E2 A 34
E3 B 34
131