Blower Motor Control System
BLOWER MOTOR CONTROL SYSTEMSystem Description
SYSTEM DESCRIPTION
Component Parts
Blower speed control system components are:
- A/C auto amp.
- A/C and AV switch assembly
- Variable blower control
- Front blower motor relay
- Front blower motor
- In-vehicle sensor
- Ambient sensor
- Optical sensor
- Intake sensor
System Operation
Automatic Mode
In the automatic mode, the blower motor speed is calculated by the A/C auto amp. and variable blower control based on input from the in-vehicle sensor, optical sensor, intake sensor and ambient sensor, and potentio temperature control (PTC).
When the air flow is increased, the blower motor speed is adjusted gradually to prevent a sudden increase in air flow.
In addition to manual air flow control and the usual automatic air flow control, starting air flow control, low water temperature starting control and high passenger compartment temperature starting control are available.
Starting Blower Speed Control
Start up from cold soak condition (Automatic mode).
In a cold start up condition where the engine coolant temperature is below 50 °C (122 °F), the blower will not operate at blower speed 1 for a short period of time (up to 210 seconds). The exact start delay time varies depending on the ambient and engine coolant temperatures. In the most extreme case (very low ambient temperature) the blower starting delay will be 210 seconds as described above. After the coolant temperature reaches 50 °C (122 °F), or the 210 seconds has elapsed, the blower speed will increase to the objective blower speed.
Start up from usual operating or hot soak condition (Automatic mode).
The blower will begin operation momentarily after the AUTO switch is pushed. The blower speed will gradually rise to the objective speed over a time period of 3 seconds or less (actual time depends on the objective blower speed).
Blower Speed Compensation - Sunload
When the in-vehicle temperature and the set temperature are very close, the blower will be operating at low speed. The speed will vary depending on the sunload. During conditions of low or no sunload, the blower operates at low speed. During high sunload conditions, the A/C auto amp. causes the blower speed to increase.
Blower Speed Control Specification
COMPONENT DESCRIPTION
Variable Blower Control
The variable blower control is located on the cooling unit. The variable blower control receives a gate voltage from the A/C auto amp. to steplessly maintain the blower motor voltage in the 0 to 5 volt range (approx.).
Front Blower Motor Component Function Check
INSPECTION FLOW
Step 1-4:
Step 4 (Continued)-8:
Front Blower Motor Diagnosis Procedure
SYMPTOM: Blower motor operation is malfunctioning.
DIAGNOSTIC PROCEDURE FOR BLOWER MOTOR
Step 1-6:
Step 6 (Continued)-11:
Step 11 (Continued)-14:
Front Blower Motor Component Inspection
COMPONENT INSPECTION
Check continuity between terminals by supplying 12 volts and ground to coil side terminals of relay.
Front Blower Motor
Confirm smooth rotation of the blower motor.
- Ensure that there are no foreign particles inside the blower unit.
- Apply 12 volts to terminal 2 and ground to terminal 1 and verify that the motor operates freely and quietly.
Rear Blower Motor Description
SYSTEM DESCRIPTION
Component Parts
Rear blower speed control system components are:
- A/C auto amp.
- A/C and AV switch assembly
- Rear air control (front)
- Rear air control (rear)
- Variable blower control (rear)
- Rear blower motor
- Rear blower motor relay
System Operation
Rear Blower Control
When the rear blower control dial (front) REAR CTRL switch is pressed (indicator on), it allows the rear air control (rear) to control the rear blower motor speed. If the REAR CTRL switch is off (indicator off), the rear air control (front) controls the rear blower motor speed regardless of the rear air control (rear) position.
Rear Blower motor Component Function Check
INSPECTION FLOW
SYMPTOM:
- Rear blower motor does not operate from the rear air control (front) and the rear air control (rear).
- Rear blower motor operates from rear air control (front) only.
- Rear blower motor operates in high at all times.
INSPECTION FLOW
Step 1-3:
Step 3 (Continued)-4:
Rear Air Control (Front) Diagnosis Procedure #1
Step 1-4:
Step 4 (Continued)-7:
Rear Air Control (Rear) Diagnosis Procedure #2
REAR AIR CONTROL (REAR) INOPERATIVE
Step 1-4:
Rear Blower Motor Component Inspection
COMPONENT INSPECTION
Rear Blower Motor Relay
Check circuit continuity between terminals by supplying 12 volts and ground to coil side terminals of relays.
Rear Blower Motor
Check that there are no foreign particles inside the intake unit.
Apply 12 volts to terminal 2 and ground to terminal 1 and ensure that the blower motor rotates freely and quietly.