ASE A7 Heating Air Conditioning Practice Test

31. During a performance test on a CCOT system the manifold gauge indicates that the high side pressure is low and the low side pressure is high. This is caused by a:

  • A. Stuck open expansion valve.
  • B. Frozen expansion valve.
  • C. Restricted condenser.
  • D. Faulty compressor.

31.

Answer A is wrong. Answer D is correct. The refrigerant is metered by a fixed orifice tube. These manifold pressure readings indicate faulty reed valves in the compressor.

Answer B is wrong. The refrigerant is metered by a fixed orifice tube.

Answer C is wrong. A restricted condenser results in high discharge pressure. Answer D is correct.

Answer D is correct. A high low side and a low high side indicates a faulty A/C compressor.

32. An air conditioning system blows only warm air when the heater is on high output. Technician A says this could be a faulty heater control valve. Technician B says this could be caused by the cooling system's thermostat. Who is correct?

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

32.

Answer A is wrong. Both technicians are correct

Answer B is wrong. Both technicians are correct.

Answer C is correct. A restricted heater control valve will leave a vehicle with low heater performance. A stuck open thermostat has a negative effect on the heater's performance.

Answer D is wrong. Both technicians are correct.

33. Technician A says a fixed orifice tube varies the flow of refrigerant in relation to temperature. Technician B says a fixed orifice tube is located between the condenser and the evaporator. Who is correct?

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

33.

Answer A is wrong. A fixed orifice tube provides a consistent output, based upon the size of its orifice. It's a compromise between idle and highway conditions.

Answer B is correct. The fixed orifice tube is located between the condenser and evaporator core.

Answer C is wrong. Technician B is correct.

Answer D is wrong. Technician B is correct.

34. Technician A says the expansion valve is located on the inlet port of the evaporator. Technician B says the expansion valve's temperature sensing bulb is located near the outlet port of the evaporator. Who is correct?

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

34.

Answer A is wrong. Both technicians are correct.

Answer B is wrong. Both technicians are correct.

Answer C is correct. An expansion valve is at the inlet port of the evaporator and the sensing bulb is placed on the outlet port.

Answer D is wrong. Both technicians are correct.

Diagram of automotive ac control circuit.

35. A late model vehicle is being diagnosed for poor air conditioning performance. The air temperature blend door in the circuit illustrated above has all of the following characteristics EXCEPT:

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

35.

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 types of networks. Class A is the slowest. The climate control network is typically on a Class B network with speeds up to 125 Kbps. Class C CAN operates at speeds up to 1 Mbps for engine and transmission mission critical sensor data.

Answer C is wrong. They contain microchips that allow them to receive and transmit data.

Answer D is wrong. Vehicles manufactured in 2008 contain networks that operate on the CAN protocol or Controller Area Network.