2004 COROLLA (EWD533U)
190
Air Conditioning
Current is applied at all times through the HEATER fuse to TERMINAL 5 of the HTR relay.
When the ignition SW is turned on, the current flows through the GAUGE fuse to TERMINAL 2 of the HTR relay to
TERMINAL 1 to TERMINAL 6 of the blower SW.
1. Heater Blower Motor Operation
∗ Low speed operation
When the blower SW is moved to LO position, the current flows to TERMINAL 6 of the blower SW to TERMINAL 5 to
GROUND, causing the HTR relay to turn on. This causes the current flows from the HEATER fuse to TERMINAL 5 of
the HTR relay to TERMINAL 3 to the blower motor to the blower resistor 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 6 of the blower SW to TERMINAL 5 to
GROUND, causing the HTR relay to turn on. This causes the current flows from the HEATER fuse to TERMINAL 5 of
the HTR relay to TERMINAL 3 to the blower motor to the blower resistor to TERMINAL 2 of the blower SW to
TERMINAL 5 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 flows through the HTR relay to the blower motor to the blower
resistor to TERMINAL 1 of the blower SW to TERMINAL 5 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 6 of the blower SW to TERMINAL 5 to
GROUND, causing the HTR relay to turn on.
This causes the current flows from the HEATER fuse to TERMINAL 5 of the HTR relay to TERMINAL 3 to the blower
motor to TERMINAL 4 of the blower SW to TERMINAL 5 to GROUND, rotating the blower motor at high speed.
2. Air Conditioning Operation
When the blower SW is set on, the current flows from the HTR fuse to the HTR relay (Point side) to the A/C fuse to the
TERMINAL 2 of the A/C SW. If the A/C SW is turned on, at this time a signal is input into the engine control module. This
activates the engine control module and M/G CLT relay. So that current flows from the A/C fuse to M/G CLT relay (Point side)
to A/C magnetic clutch. Causing the compressor to operate.
HTR Relay
5–3 : Closed with the ignition SW at ON position and the blower SW on
P2 Pressure SW
1–4 : Open with the refrigerant pressure at less than approx. 2.0 kgf/cm
2
(28.4 psi, 196.1 kpa) or more than
approx. 32.0 kgf/cm
2
(455 psi, 3138.1 kpa)
: Parts Location
Code See Page Code See Page Code See Page
A1 32 B3 34 E5 B 34
A8 34 B4 34 J3 35
A9 34 B5 34 J7 35
A11 34 E3 A 34 P2 33
:
Relay Blocks
Code See Page Relay Blocks (Relay Block Location)
1 22 Engine Room R/B (Engine Compartment Left)
3 28 RH R/B (Right Side of the Instrument Panel Reinforcement)
System Outline
Service Hints
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