Question 1

Technician A says suction lines connect the accumulator to the compressor. Technician B says discharge lines connect the compressor to the condenser. Who is correct?

Accepted Answer

Both technicians are correct. The suction line carries low-pressure refrigerant vapor from the evaporator to the compressor, which is connected to the accumulator. The discharge line carries high-pressure refrigerant vapor from the compressor to the condenser.

Question 2

Technician A says the normal operating pressures of R-134a are slightly lower than the pressures of R-12. Technician B says R-134a boils at 134 degrees Fahrenheit. Who is correct?

Accepted Answer

The answer of Technician A says the normal operating pressures...

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

Heater control valves are operated by a ______.

Accepted Answer

Heater control valves can be operated by a cable, a thermostat, or a vacuum motor, depending on the vehicle's design.

Question 5

On which of the following laws of nature is the air-conditioning system based?

Accepted Answer

Air-conditioning systems operate based on principles of heat flow, heat absorption, and the relationship between pressure and boiling points.

Question 6

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 7

A heating system includes all the following parts EXCEPT:

Accepted Answer

The receiver/dryer is a component of an air conditioning system, not a heating system.

Question 8

Which of the following oils can be used in an R-134a system?

Accepted Answer

PAG oil (Polyalkylene Glycol) is specifically designed for use with R-134a refrigerant systems, providing proper lubrication and compatibility.

Question 9

Which of the following statements is not correct?

Accepted Answer

The accumulator is typically located between the evaporator and the compressor, not between the condenser and the receiver/dryer.

Question 10

Which of the following may be electrically connected in series with the compressor electromagnetic clutch?

Accepted Answer

All the listed switches (ambient temperature switch, thermostatic switch, and pressure cycling switch) can be connected in series with the compressor electromagnetic clutch to control its operation based on different conditions.

Question 11

A poor heat condition is being discussed. Technician A says a disconnected engine vacuum hose could not cause the problem. Technician B says a seized blend door could cause the problem. Who is correct?

Accepted Answer

A seized blend door can cause poor heat conditions as it may prevent proper airflow through the heater core, affecting the heating system's performance. A disconnected engine vacuum hose could potentially cause other issues but not directly affect the heating system's ability to produce heat.

Question 12

Which of the following statements concerning R-12 is correct?

Accepted Answer

R-12, also known as dichlorodifluoromethane, is a chlorofluorocarbon (CFC) and is known to be destructive to the Earth's ozone layer. It is not a hydrofluorocarbon, and its boiling point is not 0 degrees Fahrenheit.

Question 13

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

The answer of Technician A says when the pressure applied...

Question 14

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.

Question 15

Which of the following statements concerning evaporators is NOT true?

Accepted Answer

High-pressure vapor does not leave the evaporator; instead, low-pressure vapor exits the evaporator after the refrigerant absorbs heat and evaporates.

Question 16

Which of the following statements is NOT correct?

Accepted Answer

The evaporator changes heated refrigerant to a gas, not a liquid. It absorbs heat from the passenger compartment, causing the refrigerant to evaporate.

Question 17

A poor heat out of the floor duct condition is being discussed. Technician A says the coolant level in the engine's cooling system may be low. Technician B says the engine's thermostat may be faulty. Who is correct?

Accepted Answer

Both Technician A and Technician B are correct. A low coolant level can lead to insufficient heat transfer, resulting in poor heating performance. A faulty thermostat can prevent the engine from reaching the proper operating temperature, also causing poor heat output.

Question 18

All materials or substances, as cold as ______, have heat in them.

Accepted Answer

-459°F (-273°C) is known as absolute zero, which is the temperature at which all molecules stop moving. However, even at this temperature, there is still some residual heat in the substance. Therefore, all materials or substances, even those as cold as absolute zero, have heat in them.

Question 19

Technician A says the thermostatic expansion valve and the fixed orifice tube perform the same function. Technician B says heat from the evaporator core surface is lost to the boiling and vaporizing refrigerant. Who is correct?

Accepted Answer

Both technicians are correct. The thermostatic expansion valve and the fixed orifice tube both regulate the flow of refrigerant into the evaporator, and heat from the evaporator core surface is indeed lost to the boiling and vaporizing refrigerant, which is a fundamental principle of how air conditioning systems operate.

Question 20

Which of the following statements is correct?

Accepted Answer

Refrigerant leaves the compressor as a high-pressure, high-temperature vapor, not a liquid. It leaves the condenser as a high-pressure, low-temperature liquid, and returns to the compressor as a low-pressure, low-temperature vapor.

Quiz 54: Heating and Air Conditioning