AUTO 207 HVAC
Based on the information in this chapter, which of the following would be an incorrect air gap between the faces of the compressor clutch armature and pulley? A. .010'' (0.25 mm) B. .030'' (.075 mm) C. .045'' (.115 mm) D. .060'' (.150 mm)
A. .010'' (.025 mm)
Technician A says an excess of electrons in one part of a complete circuit causes current flow. Technician B says current can flow through some incomplete circuits. Who is correct? A. A Only. B. B Only. C. Both A and B. D. Neither A nor B.
A. A Only.
Technician A says an aspirator pulls air over the temperature sensor using the venture principle. Technician B says pulling air over the temperature sensor causes it to generate its own current. Who is right?: A. A only B. B only C. Both A and B D. Neither A nor B
A. A only
Technician A says an excess of electrons in one part of a complete circuit causes current flow. Technician B says current can flowe through some incomplete circuits. Who is correct? A. A only B. B only C. Both A and B D. Neither A nor B
A. A only
Technician A says barrier hoses are used on all refrigeration systems originally equipped with R-134a. Technician B says barrier hoses must be installed on all systems retrofitted from R-12 to R134a. Who is right? A. A only B. B only C. Both A and B D. Neither A nor B
A. A only
Technician A says only a liquid can change state up or down. Technician B says a chemical change can also be a change of state. Who is correct? A. A only B. B only C. Both A and B D. Neither A nor B
A. A only
Technician A says only a liquid can change state up or down. Technician B says a chemical change can also be a change of state. Who is inccorect? A. A only B. B only C. Both A and B D. Neither A nor B
A. A only
Thermostatic temperature cycling switches are being discussed. Technician A says the switch uses a gas sealed in a sensing bulb and diaphragm. Technician B says the diaphragm operates the expansion valve. Who is right? A. A only B. B only C. Both A and B D. Neither A nor B
A. A only
Thermostatic temperature cycling switches are being discusses. Technician A says the switch uses a gas sealed in a sensing bulb and diaphragm. Technician B says the diaphragm operates the expansive valve. Who is right? A. A only B. B only C. Both A and B D. Neither A nor B
A. A only
Which of the following air doors is least likely to be operated by a vacuum diaphragm? A. Bend door B. Recirculation door C. resistor assembly D. blower motor stationary windings
A. Blend door
All of the following statements about R-134a and R-12 are true, except A. R-12 evaporates at a slightly higher pressure than R-134a B. R-12 condenses at a slightly higher pressure than R-134a C. an R-12 system compressor does not work as hard as an R-134a system compressor D. if environmental impact and expense are considered, R-134a is the better choice than R-12
A. R-12 evaporates at a slightly higher pressure than R-134a
If during the refrigeration system performance test you notice the cooling fan(s) are not operating, which of the following should you do next? A. Stop the performance test B. Lower the engine speed to idle C. Add coolant to the engine radiator D. Turn the HVAC switch to vent
A. Stop the performance test
The most likely condition under which the low pressure cutoff switch would cut off current to the compressor clutch is A. a refrigerant leak develops B. very high pressures develop on the low side of the system C. very high pressures develop on the high side of the system D. the compressor clutch begins slipping
A. a refrigerant leak develops
The most likely condition under which the low pressure cutoff switch would cut off current to the compressor clutch is A. a refrigerant leak develops B. very high pressures develop on the low side of the system C. very high pressures develop on the high side of the system D. the compressor clutch begins slipping
A. a refrigerant leak develops
All of the following statements about scroll compressors are true, except A. both scrolls can move B. one scroll is attached to the crankshaft in an off-center position C. the scroll circles around the crankshaft center-line in an orbital motion D. a discharge reed valve is installed in the compressor
A. both scrolls can move
The spring lock coupling contains all of the following parts, except A. compression nut B. garter spring C. female fitting D. two O-rings
A. compression nut
The fan clutch ______________ at high speeds to reduce power loss. A. disengages B. overheats C. slips D. locks up
A. disengages
On modern vehicles the blower motor runs whenever the ____________________ is running. A. engine B. compressor C. stepper motor D. water valve
A. engine
A musty smell inside of the vehicle may be caused by _____________ on the evaporator A. mold B. refrigerant C. lubricating oil D. desiccant
A. mold
All of the following statements about pressure cycling switches are true, except A. pressure cycling switches open and close the electrical circuit to the HVAC control panel B. pressure cycling switches are the most common clutch control switches C. pressure cycling switches are installed on the low side of the system D. some pressure cycling switches can be adjusted
A. pressure cycling switches open and close the elctrical circuit to the HVAC control panel
All of the following statements about pressure cycling switches are true, except A. pressure cycling switches open and close the electrical circuit to the HVAC control panel B. pressure cycling switches are the most common clutch control switches C. pressure cycling switches are installed on the low side of the system D. some pressure cycling switches can be adjusted
A. pressure cycling switches open and close the electrical circuit to the HVAC control panel
All of the following statements about axial compressors are true, except A. the wobble plate can turn on the crankshaft B. compressors with double-ended pistons have an even number on cylinders C. compressors with single ended pistons have an odd number of cylinders D. rotation of the wobble plate causes it to move back and forth
A. the wobble plate can turn on the crankshaft
All of the following statements about axial compressors are true, except A. the wobble plate can turn on the crankshaft B. compressors with double-ended pistons have an even number of cyclinders C. compressors with single ended pistons have an odd number of cyclinders D. rotation of the wobble plate causes it to move back and forth
A. the wobble plate can turn on the crankshaft
The cylinder heads must be especially well cooled to prevent A. Valve burning B. system corrosion C. excessive heater output D. water pump damage
A. valve burning
Which of the following is the best description of the purpose of the accumulator oil return hole? A. Allows refrigerant to return to the compressor AB. Allows oil to return to the compressor C. Traps debris in the accumlator D. Separates liquid and vaporized refrigerant
B. Allows oil to return to the compressor
Technician A says changing refrigerant from a gas to a liquid causes it to absorb heat. Technician B says the system refrigerant is used over and over. Who is correct? A. A only B. B only C. Both A and B D. Neither A nor B
B. B only
Technician A says double-ended pistons are used on radical compressors. Technician B says need valves are used on all piston compressors. Who is right? A. A only B. B only C. Both A and B D. Neither A nor B
B. B only
Technician A says high refrigeration system static pressure indicates the vehicle has been retrofitted. Technician B says low refrigeration system static pressure indicates a refrigeration system leak. Who is right? A. A only B. B only C. Both A and B D. Neither A nor B
B. B only
Technician A says if the pressure is held constant, a substance will have different vaporizing and condensing temperatures. Technician B says higher pressures cause higher boiling points. Who is correct? A. A only B. B only C. Both A and B D. Neither A nor B
B. B only
Technician A says in series circuit, only some of the current flows through parts of the circuit. Technician B says a series-parallel circuit is a combination of series and parallel sections. Who is correct? A. A only B. B only C. Both A and B D. Neither A nor B
B. B only
Technician A says that a spectrograph can measure coolant temperature. Technician B says that a hydrometer can measure coolant freezing point. Who is correct? A. A only B. B only C. Both A and B D. Neither A nor B
B. B only
Technician A says that the o-rings should be reused on most A/C repairs. Technician B says that the accumulation of oil residue around an A/C line connection is an indication of a leak in the system. Who is correct? A. A only B. B only C. Both A and B D. Neither A nor B
B. B only
Technician A says the capacity control valve is operated by pressure signals from the crankcase. Technician B says the capacity control valve is operated by pressure signals from the low side of the refrigeration system. Who is right? A. A only B. B only C. Both A and B D. Neither A nor B
B. B only
All of the following statements about the coolant recovery system are true, except A. Keeping air out of the cooling system reduces corrosion B. Coolant passes through the radiator pressure cap to the reach the reservoir C. Cooling system pressure is never less than outside air pressure D. The pressure cap may be installed on the reservoir tank
B. Coolant passes through the radiator pressure cap to reach the reservoir
Which of the following expansion valve parts is used to prevent evaporator flooding? A. Superheat spring B. Equalizer passage C. Sensing bulb D. Capillary tube
B. Equalizer passage
When water vapor condenses on the evaporator, which of the following happens? A. It turns to ice B. It releases latent heat C. It absorbs latent heat D. The water drips on the condenser
B. It releases latent heat
An electronic leak detector being used to check for leaks. The detector begins to squeal loudly. Which of the following is the most likely cause? A. Low detector battery B. Severe refrigerant leak C. Slight refrigerant leak D. Presence of contaminated refrigerant
B. Severe refrigerant leak
Which of the following air doors is used to select airflow from the heater outlet or air conditioner vents? A. Bend door B. Upper and lower mode doors C. Heater-defroster door D. Recirculation door
B. Upper and lower mode doors
The squirrel cage blower wheel is attached to the A. blower case B. blower motor armature C. resistor assembly D. blower motor stationary windings
B. blower motor armature
The sight glass is used to determine the refrigerant A. cleanliness B. charge level C. temperature D. flow direction
B. charge level
All of the following are types of belt drives, except A. serpentine B. elctromagnetic C. V-belt D. double V-belt
B. electromagnetic
The accumulator is located close to the A. evaporator inlet B. evaporator outlet C. condenser inlet D. condenser outlet
B. evaporator outlet
All of the following statements about compressors are true, except A. every compressor has a crankshaft B. every compressors has pistons C. all compressors use a front lip seal D. all compressors have an electromagnetic clutch
B. every compressor has pistons
All of the following statements about compressors are true, except A. every compressor has a crankshaft B. every compressor has pistons C. all compressors use a front lip seal D. all compressors have an electromagnetic clutch
B. every compressor has pistons
All of the following statements about the temperature control loop are true, except A. input sensors measure passenger compartment and ambient air temperature B. input sensors convert temperature into a voltage signal C. the driver also inputs desired temperature and operating mode information D. the computer always makes output decisions based on inputs
B. input sensors convert temperature into a voltage signal
All of the statements about metal refrigerant lines are true, except A. metal lines connect parts that do not move in relation to each other B. metal lines are more expensive than hoses C. metal lines may be held by clips D. metal lines can make tighter turns than hoses
B. metal lines are more expensive than hoses
A reed valve is opened and closed by A. oil pressure B. refrigerant pressure C. a guide rod D. an electromagnet
B. refrigerant pressure
All of the following statements about HVAC blower speed control are true, except A. electrical resistors are used to control blower motor speed B. selecting high blower speed causes the current to flow through a large resistor C. on a few HVAC systems, energizing different windings in the motor controls motor speed D. some modern HVAC blowers are controlled through a computer
B. selecting high blower speed causes the current to flow through a large resistor
The temperature control computer sends control commands to all of the following except A. blend door B. sunload sensor C. compressor clutch D. heater shutoff valve
B. sunload sensor
All of the following statements about thermistor type sensors are true, except A. thermistor resistor material respons quickly to temperature changes B. thermistor resistance goes down as its temperature decreases C. thermistor resistance is quickly affected by changes in temperature D. changes in temperature affect the amount of current traveling through the thermistor
B. thermistor resistance goes down as its temperature
The high pressure cutoff switch contacts will open when system pressure are A. too low B. too high C. normal D. varies with refrigerant temperature
B. too high
The sunload sensor is usually located on the A. cowl B. upper dashboard C. front of the radiator D. rear package shelf
B. upper dashboard
Which of the following devices is used to perform open loop flushing? A. Refrigerant cycling machine B. Recovery and recycling machine C. Blowgun D. Parts solvent
C. Blowgun
Evaporators with expansion valves are being discussed. Technician A says the sensing bulb is located at the outlet tube of the evaporator. Technician B says the bulb can be clamped to the tube exterior and covered with insulation. Who is right? A. A only B. B only C. Both A and B D. Neither A nor B
C. Both A and B
Evaporators with expansion valves are being discusses. Technician A says the sensing bulb is located at the outlet tube of the evaporator. Technician B says the bulb can be clamped to the tube exterior and covered with insulation. Who is right? A. A only B. B only C. Both A and B D. Neither A nor B
C. Both A and B
Technciian A says PAG can be used with R-134a. Technician B says PAG oil cannot be used with R-12. Who is right? A. A only B. B only C. Both A and B D. Neither A nor B
C. Both A and B
Technician A says PAG oil can be used with R-134a. Technician B says PAG cannot be used with R-12. Who is right? A. A only B. B only C. Both A and B D. Neither A nor B
C. Both A and B
Technician A says Schrader valves are used on R-134a system service valves. Technician B says every type of refrigerant is supposed to have a different service connection. Who is right? A. A only B. B only C. Both A and B D. Neither A nor B
C. Both A and B
Technician A says a computer driver is a type of power transistor. Technician B says a computer driver is a type of relay. Who is right? A. A only B. B only C. Both A and B D. Neither A nor B
C. Both A and B
Technician A says disconnecting the blower on a system with an evaporator pressure control device should cause the evaporator pressure to drop to about 28-30 psi (193-207 kPa). Technician B says disconnecting the blower on a system with evaporator pressure control device should make the clutch cycle off in about 30 seconds. Who is right? A. A only B. B only C. Both A and B D. Neither A nor B
C. Both A and B
Technician A says heat always travels from a warmer object to a colder one. Technician B says when all objects in an area at the same temperature, no heat transfer will occur. Who is correct? A. A only B. B only C. Both A and B D. Neither A nor B
C. Both A and B
Technician A says modern thermostats remain closed until coolant temperature is as high as 180 degrees fahrenheit (82 degrees celcius). Technician B says once the engine is completely warmed up, the thermostat has no effect on cooling system operation. Who is right? A. A only B. B only C. Both A and B D. Neither A nor B
C. Both A and B
Technician A says modern thermostats remain closed until coolant temperature is as high as 180 degrees fahrenheit (82 degrees celsius). Technician B says once the engine is completely warmed up, the thermostat has no effect on cooling system operation. Who is right? A. A only B. B only C. Both A and B D. Neither A nor B
C. Both A and B
Technician A says semiconductors are insulators. Technician B says semiconductors are conductors. Who is correct? A. A only B. B only C. Both A and B D. Neither A nor B
C. Both A and B
Technician A says some refrigerant blends contain R-134a. Technician B says some refrigerant blends contain R-22. Who is right? A. A only B. B only C. Both A and B D. Neither A nor B
C. Both A and B
Which is used to ensure the armature plate does not spin on the crankshaft? A. Electromagnet B. Flexible connection C. Key and keyway D. Double V-belt
C. Key and keyway
All of the following statements about latent heat are true, except A. latent heat is often called hidden heat B. solids contain no latent heat C. changes of state release a small amount of latent heat D. adding or removing latent heat does not change the temperature of a substance
C. changes of state release a small amount of latent heat
All of the following statements about latent heat are true, except: A. latent heat is often called hidden heat B. solids contain no latent heat C. changes of state release a small amount of latent heat D. adding or removing latent heat does not change temperature of a substance
C. changes of state release a small amount of latent heat
Amperage is the number of ________________ flowing past a point in a circuit. A. volts B. protons C. electrons D. atoms
C. electons
Amperage is the number of ____________ flowing past a point in a circuit. A. volts B. protons C. electrons D. atoms
C. electrons
All of the following are good questions to ask the driver to help with diagnosis, except A. does it happen whenever the engine running B. do you hear any unusual noises? C. how do you plan to pay for this? D. does this air come out of the vents or somewhere else
C. how do you plan to pay for this?
Moving the blend door to the open position causes the air to be A. cooled B. dehumidified C. reheated D. recooled
C. reheated
The blend door controls the ___________ of the air entering the passenger compartment. A. speed B. moisture C. temperature D. direction
C. temperature
All of the following statements about the refrigerant compressor are true, except A. the compressor is a pump B. the compressor moves the refrigerant through the system C. the compressor condenses the vaporized refrigerant D. refrigerant leaves the compressor as high pressure, high temperature vapor
C. the compressor condenses the vaporized refrigerant
All of the following statements about the refrigerant compressor are true, except: A. the compressor is a pump B. the compressor moves the refrigerant through the system C. the compressor condenses the vaporized refrigerant D. refrigerant leaves the compressor as high pressure, high temperature vapor
C. the compressor condenses the vaporized refrigerant
All of the following statements about control loops are true, except A. a control loop is acircle of causes and effects B. control loops are used to operate vehicle systems C. the input sensors make decisions and send commands to the output devices D. the computer can operate several control loops at the same time
C. the input sensors make decisions and send commands to the output devices
All of the following statements about control loops are true, except: A. a control loop is a circle of causes and effects B. control loops are used to operate vehicle systems C. the input sensors make decisions and send commands to the output devices D. the computer can operate several control loops at the same time
C. the input sensors make decisions and send commands to the output devices
All of the following statements about expansion valves are true, except A. the passage between the high and low sides is partially blocked by a small valve B. the valve is attached to a flexible diaphragm C. the sensing bulb is installed on the inlet end of the evaporator D. a capillary tube connects the sensing bulb and diaphragm
C. the sensing bulb is installed on the inlet end of the evaporator
All of the following statements about expansion valves are true, except A. the passage between the high ans low sides is partially blocked by a small valve B. the valve is attached to a flexible diaphragm C. the sensing bulb is installed on the inlet end of the evaporator D. a capillary tube connects the sensing bulb and diaphragm
C. the sensing bulb is installed on the inlet end of the evaporator
All of the following are preliminary steps for the refrigeration system performance check, except A. set the parking brake B. install a temperature gauge in the vent nearest the evaporator C. turn the HVAC control panel settings to the off positions D. open the front windows
C. turn the HVAC control panel settings to the off positions
Leak detector dye is usually colored A. red B. green C. orange D. All of the above
D. All of the above
None of the components of an HVAC system operate when the main panel switch is turned on. Which of the following is the least likely cause? A. Defective panel switch B. Blown HVAC fuse C. Disconnected HVAC panel connector D. Blower motor burned out
D. Blower motor burned out
Desiccant is placed in a porous bag inside the A. Accumulator B. receiver-drier C. evaporator housing D. Both A and B
D. Both A and B
the temperature control computer will display trouble codes in what mode? A. AUTO B. ECON C. DEFOG D. None of the above
D. None of the above
Refrigeration system pressures are correct on a cycling clutch type refrigeration system. No cool air is coming from the vent. Which of the following is the least likely cause? A. Blend door cable broken B. Dirt on the evaporator C. Disconnected vacuum line at the heater/air conditioner door D. Plugged orifice tube
D. Plugged orifice tube
All of the following statements about the coolant recovery system are true, except A. Keeping air out of the cooling system reduces corrosion B. Coolant passes through the radiator pressure cap to reach the reservoir C. Cooling system pressure is never less than outside air pressure D. The pressure cap may be installed on the reservoir tank
D. The pressure cap may be installed on the reservoir tank
The usual way to cause a change of state is by adding or removing _____________. A. pressure B. refrigerant C. air flow D. heat
D. heat
The usual way to cause a change of state is by adding or removing _________________ A. pressure B. refrigerant C. air flow D. heat
D. heat
Refrigerant blends may contain percentages of the following compounds, except A. propane B. chlorine C. butane D. nitrogen
D. nitrogen
When the defrost or defog mode is being sued, all of the following is happening, except: A. the refrigeration system is operating B. air is flowing through the defroster vents C. the evaporator is cooling the incoming air D. the heater shutoff valve is closed
D. the heater shutoff valve is closed
When the defrost or defog mode is being used, all of the following is happening, except A. the refrigeration system is operating B. air is flowing through the defroster vents C. the evaporator is cooling the incoming air D. the heater shutoff valve is closed
D. the heater shutoff valve is closed
All of the following statements about heat are true, except A. all substances are made up of atoms B. all molecules vibrate C. the vibration of molecules can be felt as heat D. the less molecular vibration, the more heat
D. the less molecular vibration, the more heat
All of the following statements about heat are true, except: A. all substances are made up of atoms B. all molecules vibrate C. the vibration of molecules can be felt as heat D. the less molecular vibration, the more heat
D. the less molecular vibration, the more heat
