Name: Class: Date: 4. The radiation process is not affected by the surrounding air temperature.

Transcription

1 Name: Class: Date: A/C Final True/False Indicate whether the statement is true or false. 1. Heat is removed from the body by the process of evaporation. 2. Gravity causes warm air to sink. 3. Specific heat is the same as sensible heat. 4. The radiation process is not affected by the surrounding air temperature. 5. Heat is the absence of cold. 6. To safeguard other cooling system components, a defective pressure cap should be replaced with one having a lower pressure rating. 7. Thermostats open and close gradually as the temperature of the coolant increases or decreases. 8. Some radiator fan motors will start and run without warning. 9. The most common cooling system problems are the result of leaks. 10. The engine cooling system is designed to remove about 80 percent of the total engine heat. 11. The temperature rating marked on a thermostat is the temperature at which it begins to open. 12. The low-side gauge is capable of reading a vacuum when necessary. 13. A modern air conditioner system will have either an accumulator or a receiver-drier but not both. 14. There is a direct relationship between temperature and pressure in an automotive air conditioning system. 15. When relative humidity is high, the air conditioner must work harder than when relative humidity is low. 16. Accumulators are used with expansion valve systems. 17. The receiver-dryer is located on the low-pressure side of the system. 18. The accumulator contains low-pressure vapor. 19. The compressor separates the low side from the high side of the system. 20. An H valve is often referred to as a block valve. 1

2 Name: 21. If the evaporator is starved, superheat is very high. 22. Tubing with a nylon lining can be used with both R-12 (CFC-12) and R-134a (HFC-134a) refrigerants. 23. O-rings will not usually leak if they are reused. 24. The correct oil for use with R-134a is mineral oil. 25. Most early R-12 hoses were not barrier hoses. 26. The expansion valve regulates the evaporator temperature based on the thermal heat load it detects. 27. The electronic (halogen) leak detector is the most expensive and sensitive of all leak detection devices. 28. R-134a is more likely to absorb moisture than R A leak may be marked by the presence of refrigeration oil. 30. When the air conditioning system is operating, the suction line should feel hot to the touch. 31. System malfunctions cannot be detected by visual inspection. 32. Refrigerant vapors are lighter than air. 33. R-134a and R-12 systems use the same refrigerant oil. 34. The pressure of the bulk recovery tank can be tested to identify refrigerant cross contamination. 35. Refrigeration oil circulates with the refrigerant through the system. 36. The outlet of the metering device is usually the coolest part of the system under normal operating conditions. 37. On a cycling-clutch system, the desired average temperature of the evaporator should be about 35 F (1.7 C). 38. Poor passenger compartment cooling may be the result of dirt or debris plugging the evaporator core cooling fins. 39. Restricted airflow through the condenser core will result in higher than normal high-side pressures. 40. High-side restrictions can cause extremely high temperatures. 41. Moisture in a refrigerant system may cause intermittent poor system performance. 42. Some compressor noise is normal during regular operation. 43. The basic purpose of reciprocating piston, scroll, and rotary vane compressors is the same. 2

3 Name: 44. Liquid refrigerant may cause severe damage to the compressor. 45. Snap rings may be installed backward to increase their holding power. 46. Turning the compressor axial plate has the same effect on the pistons as turning a crankshaft. 47. Broken compressor discharge valves are a rare defect. 48. The most common type of compressors used on todays vehicles is the cam lock design. 49. Compressor oil level should be checked routinely. 50. If a bearing shows signs of excessive noise, binding, or looseness, it should be regreased. Multiple Choice Identify the choice that best completes the statement or answers the question. 1. How is heat transfer by convection accomplished? a. Heat travels by infrared rays. b. Heat travels by radio waves. c. Heat travels through the surroundind air. d. The coller and warmer objects are touching. 2. Technician A says latent heat is hidden heat. Technician B says latent heat is required for a change of state. Who is correct? 3. All of the following statements about oxygen are true, EXCEPT: a. Oxygen makes up 78 percent of the air we breathe. b. Oxygen is essential to all animal life. c. Oxygen combines readily with other elements to form complex chemicals. d. Oxygen is normally a gas. 4. The acceptable comfort range for the human body is: a percent relative humidity c. Both A and B b. 72 F-80 F d. Neither A nor B 5. The sun heats the earth through the process of a. convection. c. radiation. b. conduction. d. all of the above. 6. Technician A says sensible heat can be measured. Technician B says specific heat is the amount of heat required to change one pound of a substance by 1 F. Who is correct? 3

4 Name: 7. Technician A says convection may occur in liquids and gases. Technician B says conduction can occur between two substances that are at different temperatures. Who is correct? 8. The ideal relative humidity is between and percent. a. 10, 100 c. 30, 70 b. 20, 80 d. 40, Evaporation is being discussed. Technician A says heat is lost when evaporation occurs. Technician B says the rate of evaporation is not affected by air movement. Who is correct? 10. Technician A says excessive engine heat is a product of combustion. Technician B says the average automotive engine is only 15 percent efficient. Who is correct? 11. All of the following statements about engine cooling are true, EXCEPT: a. Engine heat is transferred to the coolant. b. Coolant heat is transferred to the ambient air. c. Heat transfer is through conduction and radiation. d. Much of the heat generated in the engine leaves through the exhaust system. 12. All of the follow are true about engine thermostats EXCEPT: a. A thermostat may be removed from a system if it is running hot. b. A faulty thermostat will effect vehicle emissions. c. A stuck closed thermostat will cause engine overheating. d. A stuck open thermostat will cause engine overcooling. 13. The two basic design types of radiators are a. down flow and cross flow. c. cross flow and recirculating flow. b. up flow and down flow. d. up flow and cross flow. 14. After a vehicle has been driven for miles, the heater still continues to blow cool air. Which of the following is the most likely cause? a. Faulty water pump impellers. c. Thermostat stuck closed. b. Partially blocked radiator. d. Partially blocked heater core. 15. Technician A says a defective radiator cap vacuum valve may cause hoses to collapse. Technician B says a defective pressure valve may cause coolant boil over and loss. Who is correct? 16. Engine coolant is designed to provide all of the following EXCEPT: a. Lower the freezing temperature of the solution. b. Inhibit rust and corrosion. c. Provide water pump lubrication. d. Lower the boiling point of the solution. 4

5 Name: 17. Technician A says the primary purpose of a thermostat is to cause the engine to warm up as soon as possible. Technician B says the thermostat should be removed from the cooling system only if the engine is overheating. Who is correct? 18. An engine coolant temperature switch or air conditioner select switch is used to energize the a. blower motor. c. compressor clutch. b. radiator fan motor relay. d. dashboard warning light. 19. During a routine fluid level inspection a radiator is found to be low on coolant, but the coolant recovery tank was at the proper level. Technician A says that a faulty radiator cap could be the cause. Technician B says that a cracked radiator to recovery tank hose could be the cause. Who is correct? 20. A thermostat in the cooling system helps prevent a. overheating. c. rust formation. b. overcooling. d. heater core leaks. 21. Technician A says the cooling system must be full for a pressure test to be effective. Technician B says the cooling system should never be pressurized beyond the pressure cap rating. Who is correct? 22. A vehicles engine temperature gauge is reading higher than normal and the readiator fan does not operate. Technician A says that no continuity across the fan motor could be the cause. Technician B says that an open radiator fan fuse could be the cause. Who is correct? 23. Technician A says the CFC-12 (R-12) service manifold hose fitting must be 1/2-inch male refrigerant flare nut at each end. Technician B says HFC-134a (R-134a) service manifold hoses use an ACME female nut. Who is correct? 24. Technician A says the air conditioning system is designed to remove heat from the passenger compartment. Technician B says the air conditioning system is designed to tranfer heat absorbed to the outside air. Who is correct? 25. The temperature of superheated refrigerant is a. at its boiling point. b. above its boiling point. c. below its boiling point. d. none of the above. 5

6 Name: 26. When the air conditioning system is operating all of the following happens inside the evaporator, EXCEPT: a. the refrigerant removes heat from the outside air. b. the refrigerant changes from a vapor to a liquid. c. heat entering the refrigerant causes it to change state. d. the refrigerant absorbs heat. 27. The metering device changes high-pressure liquid to a. a low-pressure vapor. b. a low-pressure liquid. c. a high-pressure liquid. d. any of the above, depending on the outside air temperature. 28. What affect does the receiver dryer have on the refrigerant? a. Changes the refrigerant from a liquid to a vapor. b. Increases the high-side refrigerant pressure. c. Acts as a storage container for liquid refrigerant. d. None of the above. 29. Where in the system is the receiver dryer located? a. on the inlet to the condenser. b. on the outlet of the evaporator. c. on the outlet of the condenser. d. none of the above. 30. Under normal operating conditions all of the following occurs inside the evaporator, EXCEPT: a. The refrigerant removes heat from the outside air drawn across the evaporator core. b. The refrigerant changes from a vapor to a liquid. c. Heat entering the refrigerant causes it to change state. d. The refrigerant absorbs heat. 31. Performance testing on air conditioning is being discussed. Technician A says the engine should be operated at speeds over 3,000 rpm during the test. Technician B says a fan should be used to force air through the condenser and radiator. Who is correct? 32. Technician A says that the accumulator is on the high-pressure side of the refrigerant system. Technician B says that the receiver-drier is attached to the evaporator outlet on the refrigerant system. Who is correct? 33. Technician A says that an evaporator is a heat exchanger. Technician B says that a condenser is a heat exchanger. Who is correct? 34. Technician A says the amount of refrigerant flowing through an orifice tube is controlled by a remote sensing bulb. Technician B says the orifice tube is located in the liquid line between the condenser outlet and evaporator inlet. Who is correct? 6

7 Name: 35. If a system has a thermostatic expansion valve, it will also have all of the following parts, EXCEPT: a. accumulator. c. condenser. b. compressor. d. receiver-drier. 36. The term purge an air-conditioning system in general terms means to: a. Add sealant to the refrigerant system b. Recharge the refrigerant system c. Flush the refrigerant system. d. Remove the refrigerant from the system. 37. Before attempting to service an automotive air-conditioning system consider all of the following Except: a. Can customer afford the repair? b. Do you have the proper tools and equipment to service the system? c. Listen to customer complaint. d. Does your diagnosis make sense based on customer complaint. 38. Most vendors will not honor the warranty on a new or rebuilt compressor unless the is replaced at the time of service. a. accumulator c. expansion valve b. receiver-drier d. a or b 39. Refrigerant leaves the evaporator as a a. high-pressure vapor. c. low-pressure liquid. b. low-pressure vapor. d. high-pressure liquid. 40. Once the refrigerant from the air conditioning system has been recovered, which of the following should the technician do? a. Check the purity of the refrigerant in the recovery tank. b. Change the recovery unit fiters. c. Record the amount of refrigerant oil removed from the system. d. Change the receiver-drier. 41. Technician A says the valve at "A" is internally equalized. Technician B says the valve B is externally equalized. Who is correct? 7

8 Name: 42. Technician A says the tool shown is used to unlock spring-lock coupling air conditioning lines. Technician B says the tool can also be used to lock the coupling together. Who is correct? 43. The refrigerant from a vehicles A/C system is being recovered into a recovery unit. Technician A says that both the vapor and liquid tank valves on the recovery unit should be OPEN. Technician B says that both the high-side and low-side gauge valves on the manifold and gauge set should be OPEN. Who is correct? 44. Technician A says there are several condenser designs and flow paths in use today. Technician B says the only flow paths for refrigerant through the condenser s tubing is the parallel cross flow. Who is correct? 45. A leaking evaporator is being replaced. Technician A says the new o-rings should be coated with clean refrigerant oil. Technician B says the some refrigerant oil shoud be added to the system prior to recharging the system. Who is correct? 8

9 Name: 46. Refer to the figure above. Technician A says that the component identified by B is the condensor. Technician B says that the component identified by C is the accumulator. Who is correct? a. A only c. Both A and B b. B only d. Neither A nor B 9

10 Name: 47. All of the following statements about injecting a dye solution into the air conditioning system are true, EXCEPT: a. Dye is approved for automotive air conditioning system use. b. The dye affects the overall performance of the system. c. Dye is available in either yellow or red. d. A few days after injection, the dye will be visible at the point of the leak. 48. Technician A says the performance test is a way of measuring system pressures. Technician B says the performance test is a way of measuring the outside humidity. Who is correct? 49. Technician A says a soap solution must be used in well-ventilated spaces only. Technician B says leaks often occur in areas of limited access where it is difficult to use a halogen leak detector. Who is correct? 50. Technician A says that the electronic leak detector probe should be held directly against a suspected leak area during a eak test. Technician B says that the electronic leak detector requires routine calibration and probe tip inspection and maintenance. Who is correct? 51. When making system repairs, install the receiver-drier or accumulator a. first. c. after evacuating the system. b. last. d. any time. 52. An air conditioning system should be pumped down (evacuated) for a minimum of minutes. a. 10 c. 30 b. 20 d

11 Name: 53. During routine equipment inspection a technician notices that the R-134a recovery tank pressure is 115 psig at an ambient tank temperature of 85 F. Using the chart above what should the technician conclude? a. Tank pressure is normal and no action is required. b. Tank pressure is low and the tank contains the wrong refrigerant. c. Tank pressure is high and contaminated with non-condensable gas. d. Non of the above. 54. Technician A says that the recommended oil for most R-134a systems is PAG oil. Technician B says that the recommended oil for R-12 systems is mineral-based oil. Who is correct? 55. Many pieces of air conditioning service equipment can do all of the following, EXCEPT: a. refrigerant recovery. c. refrigerant reclaiming. b. refrigerant recycling. d. system evacuation. 11

12 Name: 56. Technician A says the manifold and gauge set is an important diagnostic tool. Technician B says the manifold and gauge set is an important tool for evacuating and charging the system. Who is correct? 57. Technician A says that the A/C system may be charge through the LOW side when the system is operating. Technician B says that the A/C system may be charged through the HIGH side when the system is off. Who is correct? 58. Technician A says recycled refrigerant in portable storage containers should be periodically shecked for noncondensable gas contamination. Technician B says contaminated refrigerant will not affect system performance.. Who is correct? 59. Charging the system is being discussed. Technician A says the refrigerant must be weighed (or metered) to obtain a proper charge. Technician B says overcharging the system will reduce its cooling efficiency. Who is correct? 60. Technician A says a refrigerant is considered contaminated if the refrigerant contains greater than 2 percent of foreign material(s). Technician B says moisture and air reduce the system's efficiency and are considered foreign material or contaminants. Who is correct? 61. Technician A says there is a direct relationship between the pressure and temperature of a refrigerant. Technician B says any apparent temperature-pressure relationships in a contaminated system are not valid. Who is correct? 62. Which of the following could cause very low pressures on the low side of a system equipped with an expansion valve? a. expansion valve stuck open c. compressor valves not sealing b. expansion valve stuck closed d. compressor clutch inoperative 63. An undercharged system will show which of the following gauge readings? a. low side, low; high side, low c. low side, high; high side, low b. low side, low; high side, high d. low side, high; high side, high 64. An R-134a expansion valve system that is properly charged has the following gauge readings, high-side 150 psig and low-side 42 psig and the ambient air temperature is 85 F. Which of the following is the most likely cause? a. A restricted receiver drier b. An out of adjustment temperature blend door c. A restricted condenser d. A stuck open expansion valve 12

13 Name: 65. If the low-side gauge pressure is showing a vacuum, all of the following defects could be the cause, EXCEPT: a. clogged inlet screen. c. compressor valves worn. b. expansion valve stuck closed. d. moisture in the system. 66. A pressure gauge reading of 26 psig (179 kpa) inside the evaporator of a system using R-134a means the evaporating temperature of the refrigerant is about a. 25 F ( 3.9 C). c. 35 F (1.7 C). b. 30 F ( 1.1 C). d. 40 F (4.4 C). 67. During a refrigerant system performance test it is noticed that both high-side and low-side pressure readings are about the same. Which of the following could be the possible cause? a. A restricted susction line. c. A restricted expansion vave. b. A faulty compressor. d. Moisture contamination. 68. An R-134a expansion valve system that is properly charged has the following gauge readings, high-side 320 psig and low-side 50 psig and the ambient air temperature is 80 F. Which of the following is the most likely cause? Technician A says an air flow restriction through the condenser coud be the cause. Technician B says the refrigerant system coud be overcharged. Who is correct? 69. Technician A says the pressures shown in the figure may indicate excessive moisture in the system. Technician B says the pressures indicate a possible defective metering device. Who is correct? 13

14 Name: 70. On a properly charged R-134a system an A/C performance test indicates both normal high- and low-side pressures, but poor cooling. Which of the following is the most likely cause? a. Restricted air flow through the condenser. b. Restricted air flow through the evaporator. c. A faulty compressor. d. Moisture contamination. 71. Which of the following is NOT a symptom of an overcharged air conditioning system? a. Compressor cycles rapidly when equipped with a cycling-clutch pressure switch b. Higher than normal high-side pressures c. Reduced cooling capacity under any load condition d. Early compressor failure 72. Technician A says a compressor clutch may be cycled based on refrigerant (evaporator) temperature. Technician B says the compressor clutch may be cycled based on refrigerant pressure. Who is correct? 73. Compressor clutch controls are being discussed. Technician A says a clutch may be cycled on and off based on system pressure. Technician B says some clutches will not be cycled on-off unless the driver operates the manual air conditioning control device. Who is correct? 74. The compressor pumps refrigerant as a a. liquid. c. liquid that changes to a vapor. b. vapor. d. vapor that changes to a liquid. 75. Technician A says most compressor clutches are driven from the engine crankshaft by a belt. Technician B says late model hybrid electric vehicles use an integrated electric motor to drive the compressor. Who is correct? 76. All of the following statements about variable displacement compressors are true, EXCEPT: a. Variable displacement compressor piston stroke is adjusted by an internal pressure valve. b. Variable displacement compressors do not have a cycling clutch. c. Variable displacement compressors have a cycling clutch.. d. Variable displacement compressors control evaporator pressure by varying their pumping capacity. 77. To measure and adjust compressor clutch air gap, a feeler gauge should be used. a. carbon steel c. nonmetallic b. soft steel d. none of the above 78. A technician finds an air conditioning clutch will not engage. Upon initial testing the compressor is receiving both proper power and ground at the compressor clutch electrical connector, in addition the compressor input shaft turns freely by hand. Which of the following is the most likely cause? a. Compressor clutch air gap too large. b. A locked up compressor. c. Low refrigerant level. d. A faulty pressure cycling switch. 14

15 Name: 79. Replacement compressors are being discussed. Technician A says after installing a replacement compressor the receiver drier/accumulator should also be replced. Technician B says the replacement compressor is supplied with oil, and checking the level is not necessary. Who is correct? 80. Low voltage at the compressor clutch coil could cause a. no clutch application. c. the clutch to stay engaged. b. a slipping clutch. d. a and b. 15

16 A/C Final Answer Section TRUE/FALSE 1. ANS: T PTS: 1 2. ANS: F PTS: 1 3. ANS: F PTS: 1 4. ANS: T PTS: 1 5. ANS: F PTS: 1 6. ANS: F PTS: 1 7. ANS: T PTS: 1 8. ANS: T PTS: 1 9. ANS: T PTS: ANS: F PTS: ANS: T PTS: ANS: T PTS: ANS: T PTS: ANS: T PTS: ANS: T PTS: ANS: F PTS: ANS: F PTS: ANS: T PTS: ANS: T PTS: ANS: T PTS: ANS: T PTS: ANS: T PTS: ANS: F PTS: ANS: F PTS: ANS: T PTS: ANS: T PTS: ANS: T PTS: ANS: T PTS: ANS: T PTS: ANS: F PTS: ANS: F PTS: ANS: F PTS: ANS: F PTS: ANS: T PTS: ANS: T PTS: ANS: T PTS: ANS: T PTS: ANS: T PTS: ANS: T PTS: ANS: T PTS: 1 1

17 41. ANS: T PTS: ANS: T PTS: ANS: T PTS: ANS: T PTS: ANS: F PTS: ANS: T PTS: ANS: F PTS: ANS: F PTS: ANS: F PTS: ANS: F PTS: 1 MULTIPLE CHOICE 1. ANS: C PTS: 1 2. ANS: C PTS: 1 3. ANS: A PTS: 1 4. ANS: C PTS: 1 5. ANS: C PTS: 1 6. ANS: C PTS: 1 7. ANS: C PTS: 1 8. ANS: D PTS: 1 9. ANS: A PTS: ANS: C PTS: ANS: C PTS: ANS: A PTS: ANS: A PTS: ANS: D PTS: ANS: C PTS: ANS: D PTS: ANS: A PTS: ANS: B PTS: ANS: C PTS: ANS: B PTS: ANS: C PTS: ANS: C PTS: ANS: B PTS: ANS: C PTS: ANS: B PTS: ANS: B PTS: ANS: B PTS: ANS: C PTS: ANS: C PTS: ANS: B PTS: ANS: B PTS: ANS: D PTS: 1 2

18 33. ANS: C PTS: ANS: B PTS: ANS: A PTS: ANS: D PTS: ANS: A PTS: ANS: D PTS: ANS: B PTS: ANS: C PTS: ANS: C PTS: ANS: A PTS: ANS: C PTS: ANS: A PTS: ANS: C PTS: ANS: D PTS: ANS: B PTS: ANS: A PTS: ANS: B PTS: ANS: B PTS: ANS: B PTS: ANS: C PTS: ANS: C PTS: ANS: C PTS: ANS: C PTS: ANS: C PTS: ANS: C PTS: ANS: A PTS: ANS: C PTS: ANS: C PTS: ANS: C PTS: ANS: B PTS: ANS: A PTS: ANS: D PTS: ANS: C PTS: ANS: B PTS: ANS: B PTS: ANS: C PTS: ANS: C PTS: ANS: B PTS: ANS: A PTS: ANS: C PTS: ANS: C PTS: ANS: B PTS: ANS: C PTS: ANS: C PTS: ANS: C PTS: ANS: A PTS: 1 3

19 79. ANS: A PTS: ANS: D PTS: 1 4