ASE A7 Heating Air Conditioning Practice Test

1. A CCOT system has a high high side. Technician A says to suspect the thermostatic expansion valve. Technician B says this system contains an orifice tube. Who is correct?

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

1.

Answer A is wrong. A thermostatic expansion valve is not used on (CCOT) cycling clutch orifice tube systems, it's used with TXV systems. CCOT systems use a fixed metering device; a (FOT) fixed orifice tube. An expansion valve meters refrigerant into the evaporator core according to temperature.

Answer B is correct. A clogged orifice tube will result in high high side pressure. It can become clogged with contaminants, debris from a damaged compressor, or a broken desiccant bag releasing desiccant into the refrigerant.

Answer C is wrong. Technician B is correct.

Answer D is wrong. Technician B is correct.

Diagram of automotive ac control circuit.

2. Corrosion at point A of the electrical diagram above will result in:

  • A. Excessive resistance in the splice leading to the high pressure sensor.
  • B. Voltage drop at the connector of the signal circuit for the high pressure sensor.
  • C. Excessive resistance in the reference circuit of the high pressure sensor.
  • D. Voltage drop at the connector of the ground circuit for the high pressure sensor.

2.

Answer A is wrong. The symbol indicates that component is a connector not a splice.

Answer B is correct. This is a three wire sensor. From left to right there is a ground circuit, then the signal circuit back to the control module, and the third is the 5 volt reference circuit.

Answer C is wrong. The signal circuit's connector is corroded.

Answer D is wrong. It's a sensor, A/C systems use switches that are either open or closed. They don't modify reference signals like sensor's do.

3. A vehicle's air conditioning performance is reduced at low speeds and stop lights, but cools at highway speeds. Which of these is MOST likely the cause of this condition?

  • A. A low refrigerant charge.
  • B. A missing fan shroud.
  • C. A normal condition.
  • D. A faulty compressor clutch relay.

3.

Answer A is wrong. A low refrigerant charge will result in poor performance at all speeds.

Answer B is correct. A properly fitting and fastened fan shroud is vital for good A/C and engine performance. Many of these shrouds and dams create a low pressure area behind the radiator and condenser. Loose or missing shrouds will be especially noticeable as the vehicle slows and ram air is reduced.

Answer C is wrong. Always replace a missing or damaged fan shroud, this is not a normal condition. A damaged or faulty fan clutch would result in the same symptoms. Some vehicles contain an additional fan in front of the A/C condenser.

Answer D is wrong. A weak compressor will result in poor A/C performance at all times.

4. Two technicians are discussing an inoperative electric blend door in an automatic air conditioning system. Technician A says to inspect the blend door's wiring and connections for an open circuit. Technician B says to troubleshoot this circuit with a test light. Who is correct?

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

4.

Answer A is correct. An open in the circuit would prevent the blend door's motor operation.

Answer B is wrong. Use a high-impedance multimeter to test today's sensitive computer circuits. A standard test light can draw too much current, resulting in damage to sensitive components.

Answer C is wrong. Technician A is correct.

Answer D is wrong. Technician A is correct.

5. A squeal is heard only when the compressor clutch first engages. Technician A says this is caused by a loose serpentine belt. Technician B says this is caused by a worn clutch pulley bearing. Who is correct?

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

5.

Answer A is correct. A loose serpentine belt will cause a squeal when the clutch first engages.

Answer B is wrong. A faulty pulley bearing would make a growling or squealing sound whenever the engine is running.

Answer C is wrong. Technician A is correct.

Answer D is wrong. Technician A is correct.