Section 12-02: Heating and Defrosting
1996 F-150, F-250, F-350, F-Super Duty and Bronco, F-Super Duty Motorhome Chassis Workshop Manual
DESCRIPTION AND OPERATION

Safety Precautions

 WARNING: CARBON MONOXIDE IS COLORLESS, ODORLESS AND DANGEROUS. IF IT IS NECESSARY TO OPERATE THE ENGINE WITH THE VEHICLE IN A CLOSED AREA SUCH AS A GARAGE, ALWAYS USE AN EXHAUST COLLECTOR TO VENT THE EXHAUST GASES OUTSIDE THE CLOSED AREA.

 CAUTION: Whenever components in areas of the engine compartment or instrument panel (04320) are being serviced, the battery ground cable must be disconnected to eliminate the possibility of electrical shorts, burned-up wiring and fires. Extreme care must be exercised when performing electrical tests where the battery must be connected to operate the system.

The following diagram illustrates the vacuum hose connections between the vacuum source, vacuum control motors (18A318), and A/C control (19980). The diagram also identifies the color coding of the vacuum hoses and charts the function control knob settings and vacuum application by heater control (18549) and function.

Function Control Vacuum Circuit





ItemPart NumberDescription
118476Heater Core
219A566A/C Vacuum Reservoir Tank and Bracket
319A563A/C Vacuum Check Valve
4Outside-Recirc. Door (White) (Part of Vacuum Harness)
5Vacuum Harness Connector (Part of Vacuum Harness)
6Temperature Blend Door (Cable Controlled) (Part of 18471)
7Floor/Panel Door (Part of 18471)
8Panel Vacuum Motor (Part of 18A318)
9Floor/Defrost Door (Red/Yellow) (Part of 18471)


Function Selector Valve Detent Positions
Tube ColorPort No.Function/DoorVentFloorOffMixDef
White1Recirc. O/S (Outside Air)AAVAA
Red2Floor Defrost (Side Port)VVVAA
Yellow3Floor Defrost (End Port)VVVVA
Blue4PanelVAAAA
Black5SourceVVVVV

V = Vacuum.

A = Atmosphere.