Voyager L4-2.4L VIN B (2001)
Blower Motor: Description and Operation
BLOWER MOTOR OPERATION
The Automatic Temperature Control (ATC) front and rear blower control provides continuously variable control of air flow rate to meet occupant
comfort requirements. Pulse width modulation of the blower motor power allows the front and rear blower to operate at any speed from off to full
speed. When front or rear blower operation is required, the ATC sends a PCI Bus message to the Front Control Module (FCM) requesting blower
relay ON. The FCM provides a ground for the front and rear blower motor relay coils, activating both relays. The front and rear blower relays
provide 12 volts to their respective blower motor power modules. Each module provides a 12 volt blower motor control signal to the ATC. The
ATC provides a pulse width modulated (duty-cycle) ground signal to this circuit based on climate requirements. The higher voltage on the signal
circuit (less duty-cycle ground) the lower the blower speed request. The lower voltage on the signal circuit (more duty-cycle ground) the higher the
blower speed request.
FRONT HVAC UNIT
The front compartment HVAC unit has five fully adjustable instrument panel outlets. Side-window demister outlets in the instrument panel
eliminate door ducts and door-to-instrument panel seals. A single, central mounted outlet delivers air for defrosting the windshield. Air exhausters
allow air entering at the front of the vehicle to flow out the back to the rear occupants. Models equipped with Dual-Zone and Three-Zone A/C
systems include a dust and odor air filter.
Mid-cabin comfort control directs only cooling airflow to the intermediate seat occupants through outlets at the rear of each front door trim panel.
Air is supplied to these outlets from the instrument panel through ducts in the doors that use molded seals at the instrument panel to prevent air
leakage. Wide outlets under the front seats with directional dividers distribute heated air across the floor to the intermediate seat occupants. Ducts
in the center of the vehicle under the carpet deliver air from the front compartment HVAC unit to these outlets.
Overhead outlets along the roof rails adjacent to each rear seat and three outlets in the right quarter panel near the floor distribute air to the
intermediate and rear seat occupants.
REAR HVAC UNIT
The rear A/C - heating unit provides air temperature modulation by utilizing a temperature door to allow variable proportions of cooled and heated
air to mix to achieve a desired ambient temperature. Also, a variable mode control in the rear unit allows proportioned airflow between the floor
and overhead outlets.
