250 likes | 344 Views
CHAPTER 10. AIR MANAGEMENT SYSTEM. I. System controls temp. & volume of in-car air circulation. A. Control head allows setting of: System on-off Fresh or recirculated air A/C, defrost, or heat function; Desired temp. Blower speed.
E N D
CHAPTER 10 AIR MANAGEMENT SYSTEM
I. System controls temp. & volume of in-car air circulation • A. Control head allows setting of: • System on-off • Fresh or recirculated air • A/C, defrost, or heat function; • Desired temp. • Blower speed
I. System controls temp. & volume of in-car air circulation • B. Types of controls. • Manual Control System: The driver manually moves levers, switches or dials to: • Adjust the temperature • Select air inlets • Select discharge locations • Turn the A/C compressor on and off.
I. System controls temp. & volume of in-car air circulation • B. Types of controls (continued) • Semi Automatic Systems (SATC): The driver: • Selects the desired temp. • System may operate blend door(s) and blower speed. • Driver may manually override some functions. • Driver selects air inlet and discharge
I. System controls temp. & volume of in-car air circulation • B. Types of controls (continued) • ATC systems use automatic features to make adjustments • Driver sets desired function / temperature. • System operates through an ECM (electronic control module)to adjust • Blower speed • Temperature door • Air inlet door and Mode door.
II. Cases & ducts: enclose & direct air flow • A. Air inlet section and door: controls either fresh or recirc. • Fresh air plenum at windshield base • Recirc (recirculated) air from the passenger footwell.
II. Cases & ducts: enclose & direct air flow • B. Case with plenum: encloses evaporator & heater core • 1. Contains temperature blend door: adjusts temperature. • Full warm: directs all air through heater core • Full cool: directs all air around heater core • In between: mixes air
II. Cases & ducts: enclose & direct air flow • C. Air distribution section with outlet ducts: provide locations for air delivery • A/C in instrument panel • Defrost at base of windshield • Heat at floor
III. Control head: contains switches & levers for various functions • A. Vacuum control systems use vacuum actuators at air doors; vacuum valves at control head;and plastic tube for connections • Vacuum actuators normally have 2 positions, on-off • Some have mid positions • Vacuum controls effect engine emissions
III. Control head: contains switches & levers for various functions • B. Electric control systems use electric motors at air doors; electric switches at control head; & wires for connections • All blower circuits use electric motors & controls • Traditional speed circuits use a multi-position switch, a set of resistors, & stepped speeds • modem circuits use electronic switching & infinite speeds
III. Control head: contains switches & levers for various functions • C. Early systems used mechanical, cable controls
IV. ATC, automatic temperature control • System monitors ambient and in-car temperature and sets controls to produce air at the proper temperature, delivery and volume.
IV. ATC, automatic temperature control • Sensors: monitor various temps.: thermistors change resistance value relative to temp. • Ambient sensor: measures temp, of incoming air • In-car sensor: measures air temp, inside car • Temp, dial: driver's input for desired temp. • Some systems use additional sensors
IV. ATC, automatic temperature control • Control device: electronic microprocessor (electronic control assembly, EGA) • Sensors are inputs • Actuators are outputs
IV. ATC, automatic temperature control • Actuators: same as used in manual system • Electric motors are operated directly from EGA • Vacuum actuators are operated through a series of solenoid valves or by a vacuum servo motor controlled through a transducer
V. Rear window defroster: electric grid in window glass • A. Electric flow controlled through switch with timer