AUT 136 Automotive HVAC. Chapter 9 Heating Systems. OBJECTIVES. After studying Chapter 9, the reader should be able to: Understand how the common automotive heating system works. Explain what parts make up the heating system. Understand how heater temperature is controlled. INTRODUCTION.
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After studying Chapter 9, the reader should be able to:
FIGURE 9-1 The main parts of a vehicle’s heating system are the heater core, blower, heater hoses, and in some cases heater valve. (Courtesy of Everco Industries)INTRODUCTION
FIGURE 9-2 Some heater systems use a valve (9) that can shut off the flow of hot coolant to the heater core (2). (Courtesy of Stant Manufacturing)
FIGURE 9-3 A heater control valve can be located at any of the positions shown.OPERATION
FIGURE 9-4 This hybrid vehicle has a pump/bypass that can pump hot coolant through the heater core (b, bottom) when the engine is shut off. During engine operation, the bypass valve (b, top) allows normal circulation. (Courtesy of Toyota Motor Sales USA, Inc.)OPERATION
FIGURE 9-4 (CONTINUED) This hybrid vehicle has a pump/bypass that can pump hot coolant through the heater core (b, bottom) when the engine is shut off. During engine operation, the bypass valve (b, top) allows normal circulation. (Courtesy of Toyota Motor Sales USA, Inc.)OPERATION
FIGURE 9-5 The two PTC, positive temperature coefficient, heater elements help warm the heater core of this hybrid vehicle. (Courtesy of Toyota Motor Sales USA, Inc.)OPERATION
FIGURE 9-6 Heat is transferred from the hot coolant flowing through the water tubes to warm the air flowing through the fins of the core.HEATER CORE
FIGURE 9-7 The critical dimensions needed when replacing a heater core. (Courtesy of Four Seasons)HEATER CORE
FIGURE 9-8 Two examples of the many shapes and sizes of heater cores. (Courtesy of Four Seasons)HEATER CORE
FIGURE 9-9 Heater hose uses reinforced rubber construction (a) and is available in straight or molded (b) shapes. (Courtesy of Veyance Technologies, Inc.)HOSES
FIGURE 9-10 Some vehicles use quick-connect couplings for the heater hose connections. The hose is merely slid firmly onto the connector to make the connection. It should be disconnected carefully using a suitable tool. (Courtesy of Four Seasons)HOSES
FIGURE 9-11 A heater control valve can be operated manually (a), by vacuum control (b), through a mechanical cable (c), or by a thermostatic element (d). (a courtesy of Four Seasons; b, c, and d are courtesy of Stant Manufacturing)CONTROL VALVES
FIGURE 9-12 The control panels for a vehicle with front and rear climate control systems. (Courtesy of Chrysler LLC)DUAL HEATING SYSTEMS
FIGURE 9-13 This aftermarket heater assembly (a) contains a heater core (9) and blower (1–4). An exploded view is shown in (b). (Courtesy of Red Dot)AFTERMARKET HEATING SYSTEMS
2. Two students are discussing the heater core. Student A says that a heater core is a heat exchanger much like a radiator. Student B says the coolant from the engine brings the heat to the heater core. Who is correct?
3. Two students are discussing heater hoses. Student A says that most hoses have an inside diameter of about one inch or larger. Student B says the heater core inlet hose is usually larger than the outlet. Who is correct?
4. Heater hoses are attached to the core using _________.
Which is correct?
5. Two students are discussing the heater output temperature. Student A says that a valve is used to reduce coolant flow through the core when less heat is desired. Student B says that most modern systems use a blend-air door to control the heat/cooling output. Who is correct?
6. The control for most heater control valves is either a Bowden cable or mechanical.
7. Two students are discussing heater temperature control. Student A says that a control valve will be wide open when full heat is desired. Student B says the coolant control valve should go wide open if the vacuum line is disconnected. Who is correct?
8. An aftermarket heater system consists of _________.