Question 1

Technician A says the compressor can pump both liquids and vapor. Technician B says the compressor is driven off the crankshaft by a belt. Who is correct?

Accepted Answer

Compressors in automotive air conditioning systems are designed to compress vapor, not liquids. Technician B is correct in stating that the compressor is typically driven off the crankshaft by a belt.

Question 2

Technician A repairs a leaking heater core. Technician B replaces a leaking heater core with a new core. Who is correct ?

Accepted Answer

Technician B is correct because a leaking heater core typically requires replacement with a new core to ensure a proper and long-lasting repair. Repairing a leaking heater core may not always be effective or reliable.

Question 3

Technician A says R-12 air-conditioning technicians must be certified. Technician B says R-12 air-conditioning equipment must be certified. Who is correct?

Accepted Answer

Both Technician A and Technician B are correct. Technicians working with R-12 air-conditioning systems must be certified to ensure they understand how to properly handle and dispose of the refrigerant, which is a chlorofluorocarbon (CFC) and harmful to the ozone layer. Additionally, the equipment used in servicing R-12 systems must also be certified to ensure it meets environmental safety standards and does not release CFCs into the atmosphere.

Question 4

A vehicle with insufficient heater performance is being discussed. Technician A says the problem could be a stuck-open engine thermostat. Technician B says air could be trapped inside the heater core. Who is correct?

Accepted Answer

Both Technician A and Technician B are correct. A stuck-open engine thermostat can prevent the engine from reaching its normal operating temperature, reducing the heat available for the heater. Air trapped inside the heater core can also prevent the proper flow of hot coolant through the core, reducing heater performance.

Question 5

Airflow control valves in the ventilation duct work are operated by ______.

Accepted Answer

Airflow control valves in ventilation ductwork can be operated by electric motors, vacuum motors, or cables, making all the provided options correct.

Question 6

Technician A says European and Japanese manufacturers shipping vehicles to the US will eliminate R-134a A/C systems by 2017. Technician B says the United States will switch to R-22 in 2015. Who is correct?

Accepted Answer

Technician A is correct because European and Japanese manufacturers were moving towards eliminating R-134a due to environmental regulations. Technician B is incorrect as R-22 is not used in automotive A/C systems and was being phased out due to its ozone-depleting properties.

Question 7

Technician A says when the pressure applied to a liquid is increased, the boiling point decreases. Technician B says when the pressure on a liquid is suddenly released, heat energy is absorbed into the liquid. Who is correct?

Accepted Answer

When pressure on a liquid is increased, the boiling point actually increases, not decreases. However, when pressure is suddenly released, the liquid can absorb heat energy, which can lead to a drop in temperature or even cause the liquid to boil.

Question 8

Technician A says hybrid vehicles have an electric water pump to circulate coolant through the heater core when the engine is stopped. Technician B says hybrid vehicles have a hot coolant storage tank to provide heat for the passenger compartment when the engine is shut down. Who is correct?

Accepted Answer

Both statements are correct. Hybrid vehicles often use electric water pumps to circulate coolant for cabin heating when the engine is off, and many also have a hot coolant storage tank to maintain heat for the passenger compartment without running the engine.

Question 9

Before 1994, most manufacturers used _____ as a refrigerant.

Accepted Answer

Before 1994, R-12 was the most commonly used refrigerant in air conditioning systems and other applications. It was later phased out due to its ozone-depleting properties.

Question 10

If little or no resistance is felt while operating the temperature control lever, the problem is most likely which of the following?

Accepted Answer

The lack of resistance when operating the temperature control lever typically indicates a mechanical disconnect or slippage, such as the control cables having slipped loose from the dash control or door arm. This prevents the lever from properly actuating the mechanism it controls.

Question 11

The boiling point of a liquid increases as ______.

Accepted Answer

The boiling point of a liquid increases when the pressure applied to it increases because the added pressure requires the liquid to gain more energy (or heat) to change its phase from liquid to gas.

Question 12

What type of vehicle uses heater cores with electric PTC heater strips?

Accepted Answer

Hybrids often use electric PTC (Positive Temperature Coefficient) heater strips in their heater cores because they can't always rely on engine heat for cabin heating, especially during electric-only operation.

Question 13

Variable displacement compressors are normally _____ compressors with a pivoting wobble plate.

Accepted Answer

Variable displacement compressors that use a pivoting wobble plate are typically axial compressors. This design allows for the adjustment of the compressor's displacement, making it more efficient by varying the output based on the cooling demand.

Question 14

The blower motor does not run in any fan switch position. A check with a DMM reveals that power is getting to the motor. Technician A says the motor ground is bad. Technician B says the motor is burned out. Who is correct?

Accepted Answer

Both Technician A and Technician B could be correct. If power is getting to the motor but it's not running, a bad ground could prevent the circuit from completing, which is what Technician A suggests. On the other hand, if the motor itself is burned out as Technician B suggests, it wouldn't run even if power is supplied and the ground is good.

Question 15

The refrigerant is at its lowest pressure and temperature at the ______.

Accepted Answer

The refrigerant is at its lowest pressure and temperature at the evaporator orifice (inlet) because this is where it expands and cools before entering the evaporator to absorb heat.

Question 16

Technician A says refrigerant leaves the compressor as a high-pressure liquid. Technician B says the condenser changes the high-pressure liquid refrigerant into a high-pressure vapor. Who is correct?

Accepted Answer

Refrigerant leaves the compressor as a high-pressure vapor, not liquid. The condenser then changes this high-pressure vapor into a high-pressure liquid, not the other way around.

Question 17

Which of these statements is true?

Accepted Answer

The answer of Which of these statements is true?
...

Question 18

Technician A says an A/C system using CO₂ [carbon dioxide] for a refrigerant will not contribute to global warming and is environmentally friendly. Technician B says CO₂ refrigerant does not need to be recovered and recycled. Who is correct?

Accepted Answer

The answer of Technician A says an A/C system using...

Question 19

Technician A says in most cases, problems with the heating system are problems with the engine's cooling system. Technician B says a restricted heater return hose can cause excess heat in the passenger compartment. Who is correct?

Accepted Answer

Technician A is correct because the heating system in a vehicle typically relies on the engine's cooling system to function properly. If there's an issue with the cooling system, it can affect the heating system. Technician B is incorrect because a restricted heater return hose would likely cause insufficient heating in the passenger compartment, not excess heat.

Question 20

Technician A says R-12 is a chlorofluorocarbon (CFC)that damages Earth's ozone layer. Technician B says R-134a is a hydrofluorocarbon (HFC)that causes even greater damage. Who is correct?

Accepted Answer

Technician A is correct because R-12 is indeed a chlorofluorocarbon (CFC) that damages the ozone layer. Technician B is incorrect because R-134a, while a greenhouse gas, does not damage the ozone layer to the extent that CFCs like R-12 do.

Quiz 54: Heating and Air Conditioning

Technician A says the compressor can pump both liquids and vapor. Technician B says the compressor is driven off the crankshaft by a belt. Who is correct?

Technician A repairs a leaking heater core. Technician B replaces a leaking heater core with a new core. Who is correct ?

Technician A says R-12 air-conditioning technicians must be certified. Technician B says R-12 air-conditioning equipment must be certified. Who is correct?

A vehicle with insufficient heater performance is being discussed. Technician A says the problem could be a stuck-open engine thermostat. Technician B says air could be trapped inside the heater core. Who is correct?

Airflow control valves in the ventilation duct work are operated by ______.

Technician A says European and Japanese manufacturers shipping vehicles to the US will eliminate R-134a A/C systems by 2017. Technician B says the United States will switch to R-22 in 2015. Who is correct?

Technician A says when the pressure applied to a liquid is increased, the boiling point decreases. Technician B says when the pressure on a liquid is suddenly released, heat energy is absorbed into the liquid. Who is correct?

Technician A says hybrid vehicles have an electric water pump to circulate coolant through the heater core when the engine is stopped. Technician B says hybrid vehicles have a hot coolant storage tank to provide heat for the passenger compartment when the engine is shut down. Who is correct?

Before 1994, most manufacturers used _____ as a refrigerant.

If little or no resistance is felt while operating the temperature control lever, the problem is most likely which of the following?

The boiling point of a liquid increases as ______.

What type of vehicle uses heater cores with electric PTC heater strips?

Variable displacement compressors are normally _____ compressors with a pivoting wobble plate.

The blower motor does not run in any fan switch position. A check with a DMM reveals that power is getting to the motor. Technician A says the motor ground is bad. Technician B says the motor is burned out. Who is correct?

The refrigerant is at its lowest pressure and temperature at the ______.

Technician A says refrigerant leaves the compressor as a high-pressure liquid. Technician B says the condenser changes the high-pressure liquid refrigerant into a high-pressure vapor. Who is correct?

Which of these statements is true?

Technician A says an A/C system using CO₂ [carbon dioxide] for a refrigerant will not contribute to global warming and is environmentally friendly. Technician B says CO₂ refrigerant does not need to be recovered and recycled. Who is correct?

Technician A says in most cases, problems with the heating system are problems with the engine's cooling system. Technician B says a restricted heater return hose can cause excess heat in the passenger compartment. Who is correct?

Technician A says R-12 is a chlorofluorocarbon (CFC) that damages Earth's ozone layer. Technician B says R-134a is a hydrofluorocarbon (HFC) that causes even greater damage. Who is correct?

Quiz 54: Heating and Air Conditioning

Technician A says the compressor can pump both liquids and vapor. Technician B says the compressor is driven off the crankshaft by a belt. Who is correct?

Technician A repairs a leaking heater core. Technician B replaces a leaking heater core with a new core. Who is correct ?

Technician A says R-12 air-conditioning technicians must be certified. Technician B says R-12 air-conditioning equipment must be certified. Who is correct?

A vehicle with insufficient heater performance is being discussed. Technician A says the problem could be a stuck-open engine thermostat. Technician B says air could be trapped inside the heater core. Who is correct?

Airflow control valves in the ventilation duct work are operated by ______.

Technician A says European and Japanese manufacturers shipping vehicles to the US will eliminate R-134a A/C systems by 2017. Technician B says the United States will switch to R-22 in 2015. Who is correct?

Technician A says when the pressure applied to a liquid is increased, the boiling point decreases. Technician B says when the pressure on a liquid is suddenly released, heat energy is absorbed into the liquid. Who is correct?

Technician A says hybrid vehicles have an electric water pump to circulate coolant through the heater core when the engine is stopped. Technician B says hybrid vehicles have a hot coolant storage tank to provide heat for the passenger compartment when the engine is shut down. Who is correct?

Before 1994, most manufacturers used _____ as a refrigerant.

If little or no resistance is felt while operating the temperature control lever, the problem is most likely which of the following?

The boiling point of a liquid increases as ______.

What type of vehicle uses heater cores with electric PTC heater strips?

Variable displacement compressors are normally _____ compressors with a pivoting wobble plate.

The blower motor does not run in any fan switch position. A check with a DMM reveals that power is getting to the motor. Technician A says the motor ground is bad. Technician B says the motor is burned out. Who is correct?

The refrigerant is at its lowest pressure and temperature at the ______.

Technician A says refrigerant leaves the compressor as a high-pressure liquid. Technician B says the condenser changes the high-pressure liquid refrigerant into a high-pressure vapor. Who is correct?

Which of these statements is true?

Technician A says an A/C system using CO2 [carbon dioxide] for a refrigerant will not contribute to global warming and is environmentally friendly. Technician B says CO2 refrigerant does not need to be recovered and recycled. Who is correct?

Technician A says in most cases, problems with the heating system are problems with the engine's cooling system. Technician B says a restricted heater return hose can cause excess heat in the passenger compartment. Who is correct?

Technician A says R-12 is a chlorofluorocarbon (CFC) that damages Earth's ozone layer. Technician B says R-134a is a hydrofluorocarbon (HFC) that causes even greater damage. Who is correct?

Technician A says an A/C system using CO₂ [carbon dioxide] for a refrigerant will not contribute to global warming and is environmentally friendly. Technician B says CO₂ refrigerant does not need to be recovered and recycled. Who is correct?