ASE A7 Heating Air Conditioning Practice Test

36. During a visual inspection an oily spot is found on a hose leading from the compressor. Technician A says there may be a refrigerant leak in the system. Technician B says today's R134a systems use mineral oil instead of the older R12 compatible PAG oil. Who is correct?

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

36.

Answer A is correct. Finding an oily spot on an A/C hose is a quick and easy way to spot a refrigerant leak. Closer inspection and testing will be necessary.

Answer B is wrong. Today's R134a air conditioning systems require PAG oil. Mineral oil is compatible with R12 refrigerant.

Answer C is wrong. Technician A is correct.

Answer D is wrong. Technician A is correct.

37. An air conditioning system contains a thermostatic expansion valve. The suction line leading to the compressor is cool to the touch. This indicates:

  • A. A stuck open expansion valve.
  • B. A low refrigerant charge.
  • C. A stuck closed expansion valve.
  • D. A normal condition.

37.

Answer A is wrong. A stuck open expansion valve will freeze the suction line and may damage the compressor.

Answer B is wrong. A low refrigerant charge would leave the line warm to the touch.

Answer C is wrong. A stuck closed expansion valve would leave the line warm to the touch and may draw the system into a vacuum.

Answer D is correct. This is a normal condition.

38. All of these are true about an accumulator EXCEPT:

  • A. It is located on the low side of the system.
  • B. It prevents excess liquid from entering the compressor.
  • C. It contains a desiccant capable of absorbing moisture from the refrigerant.
  • D. This system contains a thermostatic expansion valve to meter the refrigerant.

38.

Answer A is wrong. The accumulator is located on the low side of the system..

Answer B is wrong. It prevents excess liquid from entering the compressor.

Answer C is wrong. It contains a desiccant designed to absorb any moisture in the system.

Answer D is correct. An accumulator is used on a CCOT or Cycling Clutch Orifice Tube type system.

39. A vehicle has poor air conditioning performance. The customer has added R134a refrigerant to the system. Technician A says to use a refrigerant identifier. Technician B says refrigerant mixtures are not recommended, but will not affect system pressures. Who is correct?

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

39.

Answer A is correct. Use a refrigerant identifier to identify R12, R134a, R22, hydrocarbons and air.

Answer B is wrong. This mixture increases the system's high pressure side, resulting in high head pressure. This causes premature compressor failure.

Answer C is wrong. Technician A is correct.

Answer D is wrong. Technician A is correct.

40. An air conditioner with an expansion valve performs poorly only during the hottest times of the day. Technician A says the receiver drier may be saturated. Technician B says there may be moisture in the refrigerant. Who is correct?

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

40.

Answer A is wrong. Both technicians are correct.

Answer B is wrong. Both technicians are correct.

Answer C is correct. The receiver drier contains a desiccant that must be changed after it's been exposed to moisture. If saturated with moisture, the excessive moisture in the drier will flow to the expansion valve and freeze, reducing system performance. Poor system performance is most noticeable during the hottest times of the day.

Answer D is wrong. Both technicians are correct.