ASE A7 Heating Air Conditioning Practice Test

26. Technician A says while performing a retrofit from R-12 refrigerant to R134a refrigerant, the refrigerant must be recovered into a dedicated cylinder and not mixed. Technician B says R-12 refrigerant functions at higher pressures than R-134a refrigerant does. Who is correct?

  • A. Technician A
  • B. Technician B
  • C. Both A and B
  • D. Neither A or B

26.

Answer A is correct. The two refrigerants cannot be mixed. A separate, dedicated R-12 refrigerant container is used. Each refrigerant has its own color assignment. R-12's assignment is white, and R-134a is sky blue "light blue".

Answer B is wrong. It's the other way around, R-134a refrigerant operates at higher pressures than R-12.

Answer C is wrong. Technician A is correct.

Answer D is wrong. Technician A is correct.

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27. Technician A says an ambient temperature sensor senses cabin air temperature. Technician B says a faulty ambient temperature sensor can prevent compressor clutch engagement. Who is correct?

  • A. Technician A
  • B. Technician B
  • C. Both A and B
  • D. Neither A or B

27.

Answer A is wrong. The ambient temperature sensor uses resistance to indicate outside air temperature. If it's below a preset temperature, usually around (~50° F), the EATC will prevent clutch engagement/compressor operation and blend cool outside air instead.

Answer B is correct. The automatic temperature control module uses several input sensors. The ambient or outside air temperature sensor is a variable resistor. The automatic temperature control will not engage the compressor clutch when the outside temperature is colder than the factory set value.

Answer C is wrong. Technician B is correct.

Answer D is wrong. Technician B is correct.

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28. During an initial inspection, one line on the receiver drier is cooler than the other. This is caused by:

  • A. A refrigerant overcharge.
  • B. A low refrigerant charge.
  • C. Too much oil in the system.
  • D. A restriction in the receiver drier.

28.

Answer A is wrong. These two lines should be the same temperature.

Answer B is wrong. A restriction in the system alters the system pressure at that point, resulting in a cold or frozen spot.

Answer C is wrong. Too much oil will result in poor A/C performance.

Answer D is correct. A restriction in the receiver drier will result in a change in line temperatures. This is because one of the properties of refrigerant is that it changes temperature and pressure. The restriction has altered pressure in the drier and lowered the temperature of the outlet line.

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Electrical Symbol Variable Resister

29. The electrical symbol in the image above represents:

  • A. A thermistor.
  • B. A connector.
  • C. A diode.
  • D. A variable resistor.

29.

Answer A is wrong. It is the symbol for a variable resistor.

Answer B is wrong. Answer D is correct.

Answer C is wrong. Answer D is correct.

Answer D is correct. It's the symbol for a variable resistor. Many input sensors used by the EATC control module use variable resistance.

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30. Two technicians are discussing refrigerant storage. Technician A says HFC-134a is contained in a sky-blue container. Technician B says CFC-12 is contained in a white container. Who is correct?

  • A. Technician A
  • B. Technician B
  • C. Both A and B
  • D. Neither A or B

30.

Answer A is wrong. Both technicians are correct.

Answer B is wrong. Both technicians are correct.

Answer C is correct. (HFC-134a) R-134a is stored in a sky blue container with a sky blue label, and (CFC-12) R-12 is stored in a white container with a white label. Each refrigerant has its own color assignment. R-12's assignment is white, and R-134a is sky blue "light blue".

Answer D is wrong. Both technicians are correct.

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