Section 1 test chapters 2 & 5 A/C

All of the following are important properties that an automotive refrigerant must exhibit except: A. The refrigerant must be highly stable and allow for repeated use without decomposing or changing its properties. B. A refrigerant must be explosive or flammable. C. The critical temperature of the refrigerant must be higher than the condensation temperature of the system. D. Evaporator pressure must be higher than atmospheric pressure.

B. A refrigerant must be explosive or flammable.

All of the following are processes by which heat moves, except: A. Radiation B. Latent C. Conduction D. Convection

B. latent

In a normally operating system, the refrigerant is in different physical states (vapor or liquid) at the various sections of the system. All of the following are physical states the refrigerant would be found in at various specific locations except: A. A low-pressure vapor at the suction line B. A low-pressure vapor and/or liquid within the evaporator C. A high-pressure vapor at the discharge line D. A high-pressure liquid entering the condenser

D. A high-pressure liquid entering the condenser

Under normal operating conditions all of the following occurs inside the evaporator, except: A. The refrigerant absorbs heat. B. Heat entering the refrigerant causes it to change state. C. The refrigerant removes heat from the outside air drawn across evaporator core. D. The refrigerant changes from a vapor to a liquid.

D. The refrigerant changes from a vapor to a liquid.

All of the following are forms of heat transfer that take place as it relates to the vehicle air-conditioning system except: A. Convection B. Conduction C. Radiation D. Perspiration

D. perspiration

All of the following are gas laws, except: A. Dalton's Law B. Boyle's Law C. Darwin's Law D. Charles' Law

Darwin's Law

Technician A says that the low-side gauge may be used on the high side, if necessary. Technician B says that the high-side gauge may be used on the low side, if necessary. Who is correct?

Neither

Blue is low side (pressure) vacuum

Red is High side pressure

The metering device changes high-pressure liquid to ________________

a low pressure liquid

What is a material called that can block the flow of heat?

an insulator

Heat transfer is being discussed: Technician A says that heat flows from a hot surface to a surface containing less heat. Technician B says that heat leaves the body by the process of evaporation. Who is correct?

both

Technician A says a service information system may include estimating and shop management software. Technician B says service information you find on the Internet contains both accurate and inaccurate information. Who is correct?

both

Technician A says that the English/metric measurement unit for pressure is psig/kPa. Technician B says that the English/metric measurement unit for temperature is Fahrenheit/Centigrade.

tech A

Technician A says that the blower should be run on high speed for the performance test. Technician B says it does not matter at what speed the fan is run. Who is correct?

tech A

Technician A says that the maximum working pressure of service hoses should be 500 psig (3,448 kPa). Technician B says that 500 psig (3,448 kPa) is also the burst pressure. Who is correct?

tech A

Technician A says that the repair order is a legal document that must be filled out for every vehicle worked on. Technician B says that a repair order does not need to be filled out for a no charge (free) repair. Who is correct?

tech A

Technician A says the condenser is a heat exchanger for the superheated refrigerant in the system. Technician B says the accumulator is a heat exchanger that removes heat from the air flowing across the evaporator cooling fins. Who is correct?

tech A

Technician A says that a change in temperature from the inlet to the outlet of the thermostatic expansion valve (TXV) is not acceptable. Technician B says that a change in temperature from the inlet to the outlet of a fixed orifice tube (FOT) is acceptable. Who is correct?

tech B

Technician A says that you only need one manifold gauge set and it may be used for any type of refrigerant you need to service. Technician B says a vacuum pump is an essential piece of equipment for servicing a refrigerant system. Who is correct?

tech B

Everything in nature contains what type of heat?

specific heat

The acceptable comfort range for the human body is:

72-80 degrees F 45-50 percent relative humidity

Technician A says that a vacuum pump is used to remove moisture from a system. Technician B says that an air pump is used to remove air from a system. Who is correct?

tech A

R-134a, when used as a refrigerant, exhibits a predictable relationship between pressure and temperature, and a stable change of state point between a liquid and a gas under various pressures and temperatures. All of the following are true of the temperature pressure relationship of R-134a except: A. Refrigerant in the vapor (gaseous) state can make a change of state to a liquid by increasing the pressure on the refrigerant without changing its temperature. B. Refrigerant in the vapor (gaseous) state can make a change of state to a liquid by decreasing the temperature of the refrigerant without changing its pressure. C. Refrigerant in the liquid state can make a change of state to a gas (vapor) by increasing the pressure on the refrigerant without changing its temperature. D. Refrigerant in the liquid state can make a change of state to a gas (vapor) by increasing the temperature of the refrigerant without changing its pressure.

A. Refrigerant in the vapor (gaseous) state can make a change of state to a liquid by increasing the pressure on the refrigerant without changing its temperature.

Technician A says that a slight temperature change at the inlet and outlet of the receiver-drier indicates a restriction. Technician B says that a slight temperature change at the inlet and outlet of an accumulator indicates a restriction. Please note: Both the accumulator and receiver-drier have a filter and desiccant to pass refrigerant through. This should restrict flow slightly and cause a minor drop in pressure past the filter (or at the outlet). With a drop in pressure a drop in temperature should also be realized (minor pressure drop = minor temperature drop). If measured accurately it should not be more than a degree or two. Who is correct?

both

Technician A says that humidity has an effect on system performance. Technician B says that poor airflow has an effect on system performance. Who is correct?

both

Technician A says that latent heat is hidden heat and cannot be measured on a thermometer. Technician B says that latent heat is hidden heat that is required for a change of state of matter. Who is correct?

both

Technician A says that rules are made to protect the customer. Technician B says that rules are made to protect the technician. Who is correct?

both

Technician A says that safety glasses should be approved for gases. Technician B says that safety glasses should be approved for liquids. Who is correct?

both

Technician A says that the kPa scale is used to denote pressure on the metric gauges. Technician B says that the Hg/psig scale is used to denote pressure on the English scale. Who is correct?

both

Technician A says that the line or hose that connects the compressor outlet to the condenser inlet is called the discharge line. Technician B says that the line or hose that connects the evaporator outlet to the compressor inlet of a TXV system is called a suction line. Who is correct?

both

Technician A says that the performance test determines if system pressures are proper. Technician B says that the test determines if the system temperatures are proper. Who is correct?

both

Technician A says that you are entitled to a clean, safe place to work. Technician B says as an employee your obligation is to be a loyal, caring individual, and have the ability to follow directions. Who is correct?

both

Technician A says the compressor is one of the points in the air-conditioning system where there is a separation between a high and a low pressure. Technician B says the metering device is one of the points in the air-conditioning system where there is a separation between a high and a low pressure. Who is correct?

both

Technician A says to determine the type of refrigerant used in a system, a refrigerant identifier should be used prior to servicing the vehicle's refrigerant system. Technician B says that when working on a refrigerant system you should work in a well ventilated area. Who is correct?

both

While discussing manifold and gauge sets: Technician A says both hand valves must be closed to read service pressures. Technician B says there is a common passage on a manifold and gauge set. Who is correct?

both

what is sensible heat?

causes a change in the temperature of a substance but does not change the state of the substance

All of the following are factors that affect body comfort except:

concentration

What type of heat transfer requires air movement?

convection

what is latent heat?

is the amount of heat required to cause a change of state of a substance without changing its temperature

what is specific heat?

is the quantity of heat required to change one pound of a substance by 1 degree fahrenheit

what is convection?

is the transfer of heat by the circulation of a vapor or liquid

what is radiation?

is the transfer of heat without heating the medium through which it is transmitted

what is conduction?

is the transmission of heat through the direct contact of two objects

Technician A says that an R-12 manifold and gauge set may be used on an R-134a system. Technician B says that an R-134a manifold and gauge set may be used on an R-12 system. Who is correct?

neither

Technician A says the fixed orifice tube can vary the amount of refrigerant allowed to flow to the evaporator. Technician B says the thermostatic expansion valve has a fixed opening and cannot vary the amount of refrigerant allowed to flow to the evaporator. Who is correct?

neither

Technician A says the low-side gauge on the manifold gauge set is on the left and has a green housing. Technician B says the high-side gauge on the manifold gauge set is on the left and has a red housing. Who is correct?

neither

The heat added to a vapor causing it to become warmer is called what?

sensible heat & super heat