OBJECTIVES

2. OBJECTIVES After studying Chapter 13, the reader should be able to: • Inspect a heater system to determine whether there is proper coolant flow through the core. • Inspect a heater system to determine whether there are any coolant leaks. • Check the operation of mechanical and vacuum controls and determine whether there are any faults. • Complete the ASE tasks related to heater system diagnosis. • Complete the ASE tasks related to air management system diagnosis.

3. INTRODUCTION • Problems in the heater system or air management system can show up with improper operation of the components or during the HVAC system inspection. • Further tests can be done to determine the exact causes of these problems. • Heater Inspection • Coolant Circulation Checks • Heater Core Leak Check • Remove and Replace Heater Core • Bleeding Air from Core

4. FIGURE 13-1 Most heater system problems can be placed in one or more of these categories. INTRODUCTION

5. FIGURE 13-2 Heater output, measured at the floor outlet, should be at or above the temperatures shown. INTRODUCTION

6. FIGURE 13-3 Heater hose temperature can be checked quickly with an infrared thermometer. This return hose is 189°F, which indicates good flow through the heater core. INTRODUCTION

7. FIGURE 13-4 A special tool (a and b) is required to release the lock on quick-connect heater hose couplers. The O-rings (c) must be in good condition and lubricated with silicone to prevent leaks. (Courtesy of Four Seasons) INTRODUCTION

8. FIGURE 13-5 An alternate repair method for damaged heater hoses using quick-connect couplers is to cut off the ferrule (a), remove the damaged hose from the quick-connect nipple (b),and clamp a new hose onto the nipple (c). (Courtesy of The Gates Rubber Company) INTRODUCTION

9. FIGURE 13-6 One heater core connector is plugged as the vacuum tester pumps the core into a vacuum to test for leaks. A pressure tester can also be used in the same way. (Courtesy of Stant Manufacturing) INTRODUCTION

10. FIGURE 13-7 Some heater cores can be removed and replaced with the case still mounted (a and b). Many require that the assembly be removed; then the core is removed from the assembly and replaced (c). (a, b. Courtesy of Saturn Corporation; c. Courtesy of Chrysler LLC) INTRODUCTION

11. FIGURE 13-8 In many systems, the heater core or its hoses are above the engine’s water jackets. Loosening the upper heater hose allows the air lock to leave and coolant to enter the core. TECH TIP

12. FIGURE 13-9 This manufacturer recommends filling this rear-mounted heater core with coolant before installing it in the vehicle. (Courtesy of Chrysler LLC) TECH TIP

13. HVAC AIR FILTER REPLACEMENT • In many vehicles, filter replacement is a simple matter of opening the access panels and removing and replacing the filter element. • With some vehicles, parts such as a portion of the instrument panel or the center console must be removed. • The exact procedure is described in the service information. • The cabin filter is located either under the instrument panel or under the hood in the fresh-air plenum.

14. FIGURE 13-10 This cabin/clean-air filter is replaced by lowering the glove box door and removing a cover panel. (Provided courtesy of Toyota Motor Sales USA, Inc.) HVAC AIR FILTER REPLACEMENT

15. FIGURE 13-11 A slightly dirty filter is being removed from the fresh air chamber (a) (under hood),and a new filter is being slid into the opening (b). HVAC AIR FILTER REPLACEMENT

16. AIR MANAGEMENT SYSTEM CHECKS • Most air management system problems are related to the blower motor operation and the air doors not moving to the proper position. • The basic styles of door control are as follows: • Manual, using levers and mechanical cables • Vacuum switches, hoses, and motors • Electronic actuators and ATC or SATC using electricsolenoid-operated vacuum motors or electronic actuators

17. FIGURE 13-12 After removing the fascia panel and two retaining screws, this control head was pulled outward to gain access to the mechanical, electrical, and vacuum connections. TECH TIP • Caution should be exercised when pulling, pushing, or probing wires to prevent the unexpected. • At least one case of a technician accidentally triggering the air bags has been reported.

18. AIR MANAGEMENT SYSTEM CHECKS • Blend Door Operation • Cable Control System Checks and Adjustments • Vacuum Control System Checks

19. FIGURE 13-13 This system uses a function control cable to operate the two mode doors and a temperature cable to operate the temperature-blend door. AIR MANAGEMENT SYSTEM CHECKS

20. FIGURE 13-14 A small gap (arrow) should be between the temperature lever (full cold position) and the end of its slot if the cable is adjusted properly. AIR MANAGEMENT SYSTEM CHECKS

21. FIGURE 13-15 Most of the components of this vacuum control circuit are under the instrument panel. AIR MANAGEMENT SYSTEM CHECKS

22. FIGURE 13-16 This diagram shows the vacuum circuit during the recirculating-panel-control-head vacuum switch position. (Courtesy of Chrysler LLC) AIR MANAGEMENT SYSTEM CHECKS

23. FIGURE 13-17 Vacuum leaks can be located using a hand vacuum pump and gauge while isolating portions of the circuit using plugs or pliers. AIR MANAGEMENT SYSTEM CHECKS

24. FIGURE 13-18 Sometimes a vacuum leak can be located by listening for a “hiss” with the aid of a small hose. AIR MANAGEMENT SYSTEM CHECKS

25. AIR MANAGEMENT SYSTEM CHECKS • To troubleshoot a vacuum control system, you should: • Gain access to the vacuum selector valve, disconnect the vacuum hose harness from the selector valve, and identify the various hoses. • Connect a vacuum gauge to the hose coming from the vacuum source and start the engine. There should be at least 15 inches of vacuum. If the vacuum is less than 15 inches, repeat this check at the source vacuum locations, the intake manifold, check valve, and tank. The problem is located between the areas of adequate vacuum and inadequate vacuum. If the vacuum is 15 inches or greater at the control head, shut off the engine and note the reading. It should hold for a short period. Vacuum drop-off indicates a leak at the hose connections, tank, or check valve.

26. AIR MANAGEMENT SYSTEM CHECKS • Connect the hand vacuum pump to the vacuum hose, either for each of the vacuum actuators or just for the door actuator that is not working right, depending on the nature of the problem. Operate the pump to generate 15 to 20 inches of vacuum and, if possible, observe and listen for operation of the door actuator. • Reconnect the vacuum harness to the selector valve with the hand vacuum pump connected in place of the source vacuum hose. Move the selector valve to each of its control positions and operate the pump to determine whether a vacuum can be generated. A faulty selector valve is indicated if a circuit operates during the check in step 3 but not in this step.

27. FIGURE 13-19 With the engine running, there should be at least 15 inches of supply vacuum at the control head (a). Vacuum can be measured by probing the connector with a vacuum gauge (b). A vacuum actuator circuit should also hold the vacuum. (b. Courtesy of Chrysler LLC) AIR MANAGEMENT SYSTEM CHECKS

28. FIGURE 13-20 An actuator can be tested to see whether it operates and holds a vacuum using either a hand (a) or motorized (b) vacuum pump. (b. Courtesy of Chrysler LLC) AIR MANAGEMENT SYSTEM CHECKS

29. SUMMARY • Many heater problems are caused by leaks or poor coolant circulation. • Heater core replacement varies greatly between different vehicle models. • When coolant is changed, all of the air must be bled from the heater core. • Cabin filter replacement varies greatly between different vehicle models. • Various checks and adjustments are used to ensure proper operation of the air management system doors and actuators.

30. REVIEW QUESTIONS • Wet carpet and excessive window fogging are signs of a heater _________ _________. • Early heater core failure can be caused by _________ or _________ resulting from _________ coolant. • Poor heater output can be caused by _________ engine _________ or _________ through the heater core. • When a vehicle is operating, _________ heater hoses should be _________. • The hose connections at the heater core of some modern vehicles use _________-_________ connectors that can require a(n) _________ _________ to disconnect them.

31. REVIEW QUESTIONS • A heater core can be checked for leakage by testing it to see if it will hold either a(n) _________ or _________. • A(n) _________ _________ can prevent a heater core from filling with coolant. • An improper blend door adjustment can cause reduced _________ or _________ from the HVAC system. • When a control cable is replaced, the _________ should be checked. • A(n) _________ _________ is indicated if an actuator will not hold a vacuum.

32. CHAPTER QUIZ • Technician A says that faulty heater operation can be caused by a faulty engine cooling system. Technician B says that a complaint of insufficient heat can be caused by someone not filling a cooling system properly. Who is correct? • A only • B only • Both A and B • Neither A nor B

33. CHAPTER QUIZ • Technician A says that faulty heater operation can be caused by a faulty engine cooling system. Technician B says that a complaint of insufficient heat can be caused by someone not filling a cooling system properly. Who is correct? • A only • B only • Both A and B • Neither A nor B

34. CHAPTER QUIZ 2. Technician A says that a heater core leak can be the result of the coolant wearing a hole through the core. Technician B says that a core leak can be caused by chemical action eating a hole through the core. Who is correct? • A only • B only • Both A and B • Neither A nor B

35. CHAPTER QUIZ 2. Technician A says that a heater core leak can be the result of the coolant wearing a hole through the core. Technician B says that a core leak can be caused by chemical action eating a hole through the core. Who is correct? • A only • B only • Both A and B • Neither A nor B

36. CHAPTER QUIZ 3. Technician A says that the heater core inlet hose is connected to the water pump inlet. Technician B says that the heater inlet hose is often bigger than the outlet hose. Who is correct? • A only • B only • Both A and B • Neither A nor B

37. CHAPTER QUIZ 3. Technician A says that the heater core inlet hose is connected to the water pump inlet. Technician B says that the heater inlet hose is often bigger than the outlet hose. Who is correct? • A only • B only • Both A and B • Neither A nor B

38. CHAPTER QUIZ 4. Insufficient heat output from a heater can be caused by a(n) _____. • plugged core • faulty thermostat • air lock • Any of these

39. CHAPTER QUIZ 4. Insufficient heat output from a heater can be caused by a(n) _____. • plugged core • faulty thermostat • air lock • Any of these

40. CHAPTER QUIZ 5. Technician A says that faulty cable adjustments can cause improper heat and A/C operation. Technician B says that a broken vacuum hose can do the same thing. Who is correct? • A only • B only • Both A and B • Neither A nor B

41. CHAPTER QUIZ 5. Technician A says that faulty cable adjustments can cause improper heat and A/C operation. Technician B says that a broken vacuum hose can do the same thing. Who is correct? • A only • B only • Both A and B • Neither A nor B

42. CHAPTER QUIZ 6. A vacuum motor should _____. • move when vacuum is applied to the port • hold a vacuum Which is correct? • A only • B only • Both A and B • Neither A nor B

43. CHAPTER QUIZ 6. A vacuum motor should _____. • move when vacuum is applied to the port • hold a vacuum Which is correct? • A only • B only • Both A and B • Neither A nor B