ASE A7 Heating Air Conditioning Practice Test

1. There is little air flow through the vents of a vehicle's automatic air conditioning system. Which of the following is causing this condition?

  • A. An open in the blower motor circuit.
  • B. Resistance in the blend door motor circuit.
  • C. A faulty compressor.
  • D. A clogged cabin air filter.

1.

Answer A is wrong. An open in the blower motor circuit would prevent airflow.

Answer B is wrong. Resistance in the blend door circuit would affect cabin air temperature.

Answer C is wrong. A faulty compressor affects air temperature.

Answer D is correct. Cabin air filters get clogged with debris, restricting airflow as the system attempts to draw in the fresh air. If the fan is set on high and there's little airflow through the vents, suspect a clogged cabin air filter.

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

2.

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.

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3. 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. The accumulator is located between the condenser and the evaporator.

3.

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. A TXV system has a receiver drier located between the condenser and the evaporator

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4. A clicking sound is heard while changing the temperature setting on the air conditioning control panel. Technician A says a faulty door actuator will cause this clicking sound. Technician B says the actuator may need calibration after replacement. Who is correct?

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

4.

Answer A is wrong. Both technicians are correct.

Answer B is wrong. Both technicians are correct.

Answer C is correct. Mode door actuators will click as the gears wear and become faulty. Most of these actuators require a calibration procedure after replacement.

Answer D is wrong. Both technicians are correct.

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Diagram of automotive ac control circuit.

5. All of the following are true about the air temperature blend door in the circuit illustrated above EXCEPT:

  • A. It has a microchip and logic.
  • B. It operates on CAN Class A network.
  • C. The actuator contains a microchip and logic.
  • D. It operates on the CAN protocol.

5.

Answer A is wrong. Each motor has a unique ID. An actuator with a lower ID has priority over an actuator with a higher ID.

Answer B is correct. There are three speeds. Class A is the slowest. The climate control network is typically on a Class B network with up to 125 Kbps. Class C CAN operates up to 1 Mbps for engine and transmission critical sensor data.

Answer C is wrong. Each motor has a unique ID. An actuator with a lower ID has priority over an actuator with a higher ID.

Answer D is wrong. Vehicles manufactured in 2008 and up contain networks that operate on the CAN protocol.

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