Heating and Air Conditioning
The freezing point of water is ______ on the Celsius scale.
0 degrees
GMLAN is the General Motors term for which type of module communication?
High-speed CAN
The temperature of the refrigerant as it leaves the compressor on the discharge side should be
Hot
Heat travels from _____.
Hot to cooler
In a system that is operating correctly, the lines and hoses on the high side should be ______.
Hot to the touch
The amount of moisture contained by air is called ____.
Humidity
Where is the ambient temperature air sensor usually mounted?
In front of the radiator
Compressing a vapor______.
Increases the pressure and increases the temperatures
The amount of water that air can hold depends on ____.
The air temperature
The storage container for recovered refrigerant myst be approved by _____.
DOT
The advantages of orifice tube system over a TXV system include____.
Simpler and cheaper to produce
Heat intensity refers to which of the following?
The heat individuals feel
A ______ is a variable valve that changes the size of the calve opening in response to the cooling load of the evaporator.
Thermal Expansion Valve (TXV)
The purpose of a seat belt pretensioner is ____.
To force the occupant into position against the seat back To remove slack from the safety belt
What is the purpose of a compressor speed sensor?
To let the ECM know if the compressor is turning.
How many sensors must be triggered at the same time to cause an airbag deployment?
Two
GM Class 2 communication toggle between ______.
0 and 7 volts
A high-speed CAN BUS communicates with a scan tool through which terminal(s)?
6 and 14
Two technicians are discussing a typical non-electric fuel gauge. Tech A says if the ground wire connection to fuel tank sending unit becomes rusty or corroded, the fuel gauge will read higher than normal. Tech B says when the power lead to the fuel tank sending-unit is disconnected from the tank unit and grounded (ignition on), the fuel gauge should go to empty. Who is right?
Both Technicians
Two technicians are discussing heat movement. Tech A says that heat is a form of energy. Tech B says that heat travels from hot to cold. Who is correct?
Both Technicians
The liquid line _____.
Connects the condenser to the receiver-drier and TXV or OT Is smaller than the suction line
Pressures are controlled in an orifice tube (OT) system by _____.
Cycling an electormagnetic compressor clutch on and off as needed Using a variable displacement compressor
Heat intensity is measured in ____.
Degrees
In addition to cooling the passenger compartment, an air conditioning system _____.
Dehumidifies the air
Which condition can cause the air-conditioning system to produce less-than normal cooling?
Either undercharged or overcharged
The electrical terminals used for airbag systems are unique because they are plated with which of these metals?
Gold plated
O-rings used in R-134a systems are usually _____.
Green
When the oil pressure drops to between 3 and 7 psi, the oil pressure lamp lights by doing which of these?
Grounding one side of the gauge coil
The control module used for automatic climatic control is called _____.
HVAC control module ECM BMC
The high side of the refrigeration cycle means _____.
Has higher pressures and temperatures
Which of these is a supplemental display that projects the vehicle speed and sometimes other data, such as turn signal information, onto the windshield?
Head-up display (HUD)
As the refrigerant passes through the condenser, it ____.
Is cooled by ambient air Gives up latent heat to the air flow Condenses from a gas to a liquid
Why should service technicians check a system for the presence of sealant before recovering the refrigerant?
It can contaminate the refrigerant that is stored in the recovery container It can damage a refrigerant identifier It can harm the recover machine
The low side of the refrigeration cycle means ______.
It has low pressure and temperature
What is the SAE specification number of an RRR machine that meets the 2006 and newer standards?
J-0560
As the latent heat of condensation is transferred to the airstream in the condenser, the refrigerant makes the change into a _____.
Liquid
The refrigerant inside an evaporator is a _____.
Liquid changing to a gas
In an A/C system, the refrigerant changes state from a ____ in the evaporator.
Liquid to a gas
The refrigerant enters the evaporator as a ______.
Low-pressure mist
A module is also known as a _____.
Node
What component cannot be flushed
None of the above can be flushed
The air-conditioning process works through a fluid, called a ______ that continuously changes state from liquid to gas and back to liquid.
Refrigerant
A measurement of the actual weight on water in a given volume of air is _____.
Relative humidity
A psychrometer measures ______.
Relative humidity
What two things are accomplished in the condenser?
Remove latent heat Recycle the gas back to a liquid
The purpose of air conditioning is to _____.
Remove moisture Remove dust and pollen Remove heat
When retrofitting a system from R-12 to R-134a, what is required to be done?
Replace the receiver-drier Install a label Convert the fittings
The advantages of the TXV system over an orifice tube system include _____.
Requires a smaller refrigerant charge
The three different phases or states of matter include ____.
Solid, liquid, and gas
Which of these is a type of electric motor design to rotate in small steps based on the signal from a vehicle computer?
Stepper motor
The brake warning lamp on the dash remains on whenever the ignition is on. If the wire to the pressure differential switch is unplugged, the dash lamp goes out. Tech A says this could be a fault in the hydraulic system. Tech B says the problem is probably due to a stuck parking brake caliper switch. Who is right?
Technician A only
Tech A says LCD (Liquid Crystal Display) may be slow to work at high temperatures. Tech B says that the LCD dash display can be damaged, when pressure is exerted on the front of the display during cleaning. Who is right?
Technician B only
Tech A says that a deployed airbag can be repacked, reused, and reinstalled in a vehicle. Tech B says that a deployed airbag should be discarded and replaced with an entire new assembly. Who is right?
Technician B only
Two technicians are discussing A/C systems. Tech A says that the TXV system uses a receiver-drier mounted in the suction line. Tech B says that the orifice tube system uses an accumulator in the suction line. Who is correct?
Technician B only
Section 609 of the Act gives EPA the power to enforce ____.
Technicians are required to use approved equipment to recover and recycle CFC-12 and HFC-134a Preventing the release or venting of CFC-12 or HFC-134a Technicians who repair or service CFC-12 and HFC-134a systems must be trained and certified by an EPA-approved orginization
A BTU is a measure of ______.
Amount of heat
While diagnosing an A/C concern the scan tool reads "Inside Air Temp = 90" and "Ambient Temp = -38". Shop temperature is 87. What should the technician do?
Check the ambient sensor and connections
What maintenance should be performed to a power antenna to help keep it working correctly?
Clean the mast with a soft cloth and lubricate it with light oil
What conducts power and ground to the driver's side airbag?
Clockspring
A radio choke is actually a ____.
Coil (inductor)
Which of the following is true regarding the cabin filter?
Filter restrictions can reduce the volume of air entering the passenger compartment It is mounted in the incoming air stream from the cowl intake
A container of contaminated refrigerant should be colored
Gray with a yellow top
An antenna lead-in wire should have how many ohms of resistance between the center terminal and the grounded outer covering?
Infinity (OL)
Coolant is hottest in which area?
Near the thermostat
Which of the following is NOT a sensor in an ATC system?
Passenger sensor
Which component is used as a feedback circuit?
Potentiometer
The fitting found on an accumulator is for which of the following?
Pressure switch
Various electrical switches used in A/C systems _____.
Protect the compressor Prevent evaporating icing Control fan motors
Various electrical switches used in A/C systems _______.
Protect the compressor Prevent evaporating icing Control fan motors
A feedback potentiometer is used to______.
Provide feedback to the controller as to the location of a door or valve
Heat transferred through the air is called ______.
Radiation
An accumulator is very similar to a(n)
Receiver-drier
Which unit contains a desiccant to remove moisture from the system?
Receiver-drier Accumulator
When a compressor is replaced, it is a good practice to also replace the _____.
Receiver-drier or accumulator
The SAE standard J2788 requires improved performance from ______.
Recovery and recycling machines
Present standards and good working habits require that recovered refrigerant be _______.
Recycled
The parking brake switch is in a circuit that illuminates a ____ color light int he instrument cluster.
Red
Tech A says that backup sensors use LEDs to detect objects. Tech B says that a backup sensor will not work correctly if the paint is thicker than 0.006 inch. Who is right?
Technician B only
Tech A says that checking refrigerant odor (HC smell) is a reliable way to check for contaminated refrigerant. Tech B says that refrigerant with more than 2% of a foreign refrigerant normally should be sent off for reclaiming and disposal. Who is correct?
Technician B only
Tech A says that refrigerant charge levels are given in the owner;s manual. Tech B says that charge levels are printed on the under-hood decal. Who is correct?
Technician B only
Tech A says that the HVAC doors in an automatic system may be cable operated. Tech B says says that the HVAC doors in an automatic system may be operated by electric servos. Who is correct?
Technician B only
Terminal 16 of the OBD-II data link connector is used for what?
12 volt positive
Which terminal of the data link connector does General Motors use for Class 2 communication?
2
Driver and/or passenger front airbags will only deploy if a collision occurs how many degrees from straight ahead?
30
The freezing point of water is _____ on the Fahrenheit scale.
32 degrees
Humans prefer relative humidity that is between ____ and _____.
45%;55%
UART uses a _____ signal that toggles between 0 volts and ______.
5 volts
Most experts recommend that the system be drawn down to how many microns?
500 or lower
Humans prefer temperatures that are between ____ and ____
68F;78F
A seat belt pretensioner is ______.
A devices that contains an explosive charge Used to force the occupant back into position against the seat back in the event of a collision Used to remove slack from the seat belt in the event of a collisoin
Rear air-conditioning systems use _____.
An orifice tube to control the refrigerant flow into the front evaporator and a TXV with the rear evaporator
Where are shorting bars used?
At the connectors for airbags
A vehicle is being repaired after an airbag deployment. Tech A says that the inflator module should be handled as if it is still live. Tech B says rubber gloves should be worn to prevent skin irritation. Who is right?
Both Technicians
Tech A says most digital and analog (needle-type) dash gauges use variable resistance sensors. Tech B says Permanent-magnet (PM) generators produce an AC signal and are used for vehicle speed and wheel speed sensors. Who is right?
Both Technicians
Tech A says that some cabin filters are accessible behind the glove compartment. Tech B says that some cabin filters are accessible from under the hood. Who is correct?
Both Technicians
Tech A says that the module communication networks are used to reduce the number of wires in a vehicle. Tech B says that a communication network is used to share data from sensors, which can be used by many different modules. Who is right?
Both Technicians
CAN H and CAN L operate how?
CAN L is at 2.5 volts when not transmitting CAN H goes to 3.5 volts when transmitting CAN H is at 2.5 volts when not transmitting
Automatic temperature control (ATC) diagnosis inclueds
Check for stored diagnostic trouble codes Perform a visual inspection Verify customer concern
The refrigerant is circulated through the system by a _____.
Compressor
The orifice tube is usually located at the inlet tube to the ____.
Evaporator
When the refrigerant evaporates, it absorbs heat when it changes from liquid to gas. In which unit does this occur?
Evaporator
The sending unit in a typical fuel gauge uses which of these devices?
Float
Which sensor might use an aspirator tube?
Inside vehicle temperature
The condenser _______.
Is a heat exchanger Is a device where air passing over it cools the refrigerant and causes it to condense into a high-temperature liquid Transfers heat from the refrigerant to the air flowing
An air-conditioning system cools the interior of the vehicle by _______.
Moving the heat from the inside of the vehicle to outside the vehicle
Two technicians are discussing dual-stage airbags. Tech A says that a deployed airbag is safe to handle regardless of which stage caused the deployment of the airbag. Tech B says that both stages ignite, but at different speeds depending on the speed of the vehicle. Who is right?
Neither Technician
Every time the headlights are turned on, the dash lights get dimmer. Which of these is the MOST likely cause?
Normal behavior for VTF (Vacuum Tube Fluorescent) dash display
When an A/C system is operating, the compressor _____ runs hot
Outlet
What is the most common type of sunload sensor?
Photo diode
If the oil pressure-warning lamp remains on all the time with normal oil pressure is normal, the problem could be which of these?
Shorted wire between sending unit and sash warning lamp
Tech A says that 1 calorie of heat can increase the temperature of 1 g of water by 1F. Tech B says that the temperature will increase 1C if 1 c is added. Who is correct?
Technician B only
Desiccant is placed in the receiver-drier or accumulator-drier _______.
To absorb moisture from the system
An actuator can be capable of how many position?
Two Variable Three
What color are the airbag connectors and conduit?
Yellow
Which of these terms is a term used to describe when information is added to a constant frequency?
Modulation
Which sensor is also called the ambient air temperature sensor?
Outside air temperature
An ATC system has the ability to automatically _______.
Adjust the blower speed Change the function door setting Move the temperature-blend door
When should the service technician check for technical service bulletins?
After checking for any stored diagnostic trouble codes
100,000 µF means _____.
0.10 farad
The force required to deploy a typical airbag is approximately equal to the force of the vehicle hitting a wall at over ____ miles per hour
10
If two 4-ohm speakers are connected in parallel, meaning positive (+) to positive (+) and negative (-) to negative (-), the total impedance will be _____.
2 ohms
The temperature difference between the inlet and outlet of the condenser should be _______.
20F to 50F
Which terminal of the OBD-II data link connector is the signal ground for all vehicles.
5
What would normal low and high gauge reading be on a 90 degree day?
50 and 175 PSI
If two 4-ohm speakers are connected in series, meaning the positive (+) of one speaker is connected to the negative (-) of the other speaker, the total impedance will be _____.
8
A "pop" is heard from the radio speaker(s) when the system is operating with the air condition on. What is the most likely cause?
A defective compressor clutch diode
The upper radiator hose collapses when the engine cools. What is the most likely cause?
A defective pressure cap
A system has been evacuated and the gauge valves have been closed. A slight increase in pressure after a short time indicates ______.
A leak in the system
A container of recovered R-134a refrigerant has a pressure of 91 psi at 80 degrees F. This indicates _____.
A normal condition
How does changing tire diameter affect the speedometer reading?
A smaller diameter tire causes the speedometer to read faster than the actual speed and more than the actual mileage on the odometer.
A/C system flushing uses _____ to remove contaminants and oil from the system.
A special liquid
What should the technician use when checking for diagnostic trouble codes?
Any enhanced scan tool that can read body and/or chassis codes
What enables an airbag to deploy in an accident, even if the battery becomes disconnected during the crash?
Backup power supply
Which type of refrigerant hose is used with an R-134a system?
Barrier hose
When should a refrigerant identifier be used?
Before recovering the system
Which of these is an example of a three-position actuator?
Bi-level air door
Which of these ATC output devices provides a feedback signal to the electronic control module (ECM)?
Blend door actuator
A vacuum pump removes water from the air conditioning system by ______.
Boiling it
An aftermarket satellite radio has poor reception. Tech A says that a lack of a proper ground plane on the antenna could be the cause. Tech B says that mountains or tall buildings can interfere with reception. Who is right?
Both Technicians
Tech A says that a quick check of A/C system operation is to feel the temperature of the suction and discharge lines. Tech B says that the suction line should be cold and the discharge line hot after 5 minutes of system operation. Who is correct?
Both Technicians
Tech A says that the data displayed on the dash can come from the engine computer. Tech B says that the entire instrumental panel assembly may have to be replaced even if just one unit fails. Who is right?
Both Technicians
Tech A says that you should begin HVAC problem diagnosis with a through inspection. Tech B says that you can determine from the inspection what type of system you are dealing with. Who is correct?
Both Technicians
Two technicians are discussing TXVs. Tech A says that the TXV senses evaporator temperature to control the valve opening. Tech B says that the TXV senses evaporator pressure to control the valve opening. Who is correct?
Both Technicians
What device passes AC interference to ground and blocks DC voltage, and is used ton control radio interference?
Capacitor
The liquid line ______.
Connects the condenser to the receiver-drier and TXV or OT Is smaller than the suction line
If the oil pressure warning lamp on a General Motors vehicle is on all the time, yet the engine oil pressure is normal, the problem could be _____.
Defective (shorted) oil pressure sending unit (sensor) Wire shorted to ground between sending unit (sensor) and dash warning lamp
When servicing an airbag, which of these is the first step taken?
Disconnect the battery negative cable
Most modern vehicles use a _____ for an input to the engine temperature display.
ECT sensor
Which of the following is NOT a component of an automatic temperature control system?
Electrically operated actuators Control head Temperature sensors ALL CORRECT
Most A/C systems first pass the air through the _____ as it enters the vehicle.
Evaporator
The TXV is located at the _____.
Evaporator inlet
Adding a small can of sealant to the A/C system is a good preventive measure to stop leaks.
False
The number of times a particular waveform repeats itself in a given amount of time (frequency) is measured in ______.
Hertz
A fixed-orifice tube _____.
Is usually located in the evaporator inlet or line to the evaporator
Which of these electronic display devices uses electrodes and polarized fluid to create numbers and characters?
LED (Liquid Emitting Diode)
As the latent heat of condensation is transferred to the airstream in the condenser, the refrigerant makes the change into a ______.
Liquid
What could be wrong if the A/C compressor clutch cycles on and off rapidly?
Low refrigerant charge
Most A/C performance tests include ______.
Measure ambient temperature 3 inches (80mm) in front of the condenser and measure the humidity Start the engine, set the parking brake and raise the idle to 2,000 RPM Open the doors and set the blower speed to high which applies the maximum load on the system
A musty, moldy smell in the air-conditioning system is usually due to ______.
Mildew-type fungus growth
A faulty A/C system has a high low-side pressure and a high high-side pressure. Tech A says that the system is probably starved. Tech B says that the system has a bad thermostatic switch. Who is correct?
Neither Technician
Tech A says that a radio can receive AM signals, but not FM signals, if the antenna is defective. Tech B says that a good antenna should give a reading of about 500 ohms when tested with an ohmmeter between the center antenna wire and ground. Who is right?
Neither Technician
Tech A says that because of hybrid/electric technology, the internal combustion engine used on these vehicles runs colder than peak operating temperatures. Tech B says that the PTC coolers located in the A/C system are used to overcome this excessive engine heat. Who is right?
Neither Technician
Tech A says that retrofitting a system is simply a matter of recovering the R-12 and recharging it with a drop-in refrigerant. Tech B says that the charge level specification is the same with R-134a as with R-12. Who is correct?
Neither Technician
Tech A says that the same recovery unit can be used for R-12 and R-134a. Tech B says that the service hoses from an R-134a recovery unit must have shutoff valves within 18 inches of the end. Who is correct?
Neither Technician
While discussing a manifold gauge set, Tech A says that the high-side gauge also indicates vacuum readings. Tech B says that the low-side pressure gauge goes up to 750 psi. Who is correct?
Neither Technician
Clear water is seen dripping from beneath the vehicle on the passenger side. This means _______.
Normal operation
All of these can cause radio interference, EXCEPT _______.
Open in the radio power circuit
High-side pressure is affected by ______.
Refrigerant charge level Fan clutch operation Ambient temperature
What is the first step when servicing a vehicle refrigeration (A/C) system?
Refrigerant identification
The HVAC control module uses _____ to control high current loads in the A/C system.
Relays
The low-side pressure is low and the high-side pressure is higher than normal. What is the most likely cause?
Restriction on the high-side line
Both high-side pressures and low-side pressures are low with the engine running and the selector set to the air conditioning position. Tech A says that the system is undercharged. Tech B says the cooling fan could be inoperative. Who is correct?
Tech A only
Tech A says that a braided ground wire is best to use for audio equipment to help reduce interference. Tech B says to use insulated 14 gauge or larger grounded wire to reduce interference. Who is right?
Technician A only
Tech A says that crossovers are used to block certain frequencies to allow each type of speaker to perform its job better. Tech B says that a high-pass filter is used to block high-frequency sounds being sent to large woofer speakers, and a low-pass filter blocks low-frequency sounds being sent to tweeters. Who is right?
Technician A only
Tech A says that metal-type window tinting can affect the navigation system. Tech B says that most navigation systems require a monthly payment for use of the GPS satellite. Who is right?
Technician A only
Tech A says that oily residue on a fitting or hose can indicate a refrigerant leak. Tech B says that this residue is normal around most A/C fittings. Who is correct?
Technician A only
Tech A says that radios receive AM and FM signals that are broadcast through the air. Tech B says that the radio antenna is used to induce a very large voltage signal as an input into the radio from the electromagnetic energy from the broadcast station. Who is right?
Technician A only
Tech A says that two sensors must be triggered at the same time for an airbag deployment to occur. Tech B says that frontal airbags only operate within 60 degrees from center and do not deploy in the event of a side or rear collision. Who is right?
Technician A only
Tech A says that all O-rings are OK to use with R-134a systems. Tech B says that the color of the O-ring indicates the material it is made from. Who is correct?
Technician B only
Tech A says that FM requires an antenna whereas AM may be heard from a radio without an antenna. Tech B says that speaker reproduce the original sound and their impedance can be different. Who is right?
Technician B only
Tech A says that a system should be evacuated for twice as long if the vacuum pump will only pull down to 20"Hg. Tech B says that the system might have a leak in it if it will not pull down into a deep vacuum. Who is correct?
Technician B only
Tech A says that airbag electrical terminals are copper-plated to protect against corrosion. Tech B says that pretensioners are explosive (pyrotechnic) devices which remove the slack from the seat belt and help position the occupant. Who is right?
Technician B only
Two technicians are discussing how to remove refrigerant from a system. Tech A says that you can vent it into the atmosphere as long as it has moisture in it. Tech B says that all refrigerant must be captured. Who is correct?
Technician B only
Two technicians are discussing orifice tubes. Tech A says that the OT is always placed close to the evaporator inlet. Tech B says the OT is placed close to the condenser in some vehicles. Who is correct?
Technician B only
What is called "black death"?
Teflon from the compressor piston rings
A dual-zone A/C system allows for different ______ for the driver and passenger.
Temperatures
If an A/C system contains contaminated refrigerant, how can the contaminated refrigerant be removed?
Use a separate recovery machine that is dedicated to contaminated refrigerant recovery.
Which system utilizes a receiver-drier?
Variable Displacement Thermostatic Expansion Valve System
Several different methods of leak detection are available including _____.
Visual inspection looking for refrigerant oil stains Using a leak detector Dye
In an operating A/C system, the outlet line from the evaporator should be ______.
Warm
A ____ is the time and distance between two consecutive points, either high or low.
Wavelength
A cooling module usually includes what components?
A/C condenser Radiator Automatic transmission fluid cooler
Some cabin filters contain ____ to absorb odors.
Activated charcoal
A container of R-134a tested at a pressure of 115 PSI at an ambient temperature of 75F. This means ______.
Air is in the refriegerant
