ASE A7
A hissing noise is heard in the engine compartment for approximately one minute after the engine is shut off. Technician A says that the A/C system equalization makes an audible noise when the engine is shut off. Technician B says the heater core makes an audible noise when the engine is shut off. Who is correct?
A Only
A performance test of the A/C system is being performed on a late model vehicle. Technician A says that a thermometer should be installed into the center duct during the test. Technician B says that the A/C refrigerant should be recovered during the test. Who is correct?
A Only
A pulse width modulated electric cooling fan motor is being diagnosed. Technician A says that the HVAC control module energizes these motors by signaling a fan control driver module. Technician B says that these fans operate at two speeds. Who is correct?
A Only
A serpentine belt is being replaced and the tensioner will not snap back after being released. Technician A says that the tensioner spring could be broken and the tensioner will need to be replaced. Technician B says that the idler pulley is jammed and will need to be replaced. Who is correct?
A Only
A technician connects a scan tool to a late model vehicle to troubleshoot a problem in the ATC system. The scan tool gives a fault of "data bus short to ground." Technician A says that the problem could be a data wire rubbing against a sharp body component. Technician B says that the problem could be a broken data wire. Who is correct?
A Only
A vehicle has a problem of a stalling engine when the steering wheel is turned to full lock. This problem happens only when the air conditioning is on. Technician A says that the vehicle may have a bad power steering pressure switch. Technician B says this could occur if the power steering belt is loose. Who is correct?
A Only
A vehicle is being diagnosed for the cause of a blown fuse in the blower motor circuit. Technician A says a short to ground in the circuit caused the fuse to blow. Technician B says an open field winding in the fan motor could have caused the fuse to blow. Who is correct?
A Only
A vehicle is in the shop with the complain of the heater not being hot enough. The coolant level has been checked and is found to be full. Technician A says that the thermostat should be tested for proper operation. Technician B says that the heater control valve could be stuck open. Who is correct?
A Only
A vehicle with a faulty A/C pressure sensor is being diagnosed. Technician A says that this device is used to provide A/C pressure feedback to a control module. Technician B says that this device is typically mounted in the low side of the A/C system. Who is correct?
A Only
A vehicle with electronic dual one climate control has a problem of the passenger side only blowing hot air no matter what the passenger setting is adjusted to. Technician A says that passenger blend door actuator could be defective. Technician B says that the passenger defroster mode actuator could be defective. Who is correct?
A Only
A vehicles cooling system is being inspected during a 30,000 mile service. Technician A says that the radiator cap should be pressure tested to check for correct operation. Technician B says that the coolant freeze protection should be checked with a voltmeter. Who is correct?
A Only
An A/C compressor cycles off when the high side pressure builds. Technician A says that the high pressure cutoff switch is opening the circuit to the compressor clutch. Who is correct?
A Only
An inoperative cable controlled heater control valve is being diagnosed. The control moves freely, but the valve does not respond. Technician A says the cable housing clamp may be loose at the control head (panel) end. Technician B says the cable may be rusted in the housing. Who is correct?
A Only
Technician A says that automatic temperature control (ATC) control heads are typically a digital design. Technician B says that some automatic temperature control (ATC) systems use a cable operated heat mode actuator. Who is correct?
A Only
The heating system is being diagnosed for poor heating performance. Technician A says the problem could be a stuck open engine thermostat. Technician B says that the problem could be an inoperative cooling fan. Who is right?
A Only
A refrigerant identifier is connected to an A/C system and gives the reading of 95 percent R-134a and 5 percent R-12. Technician A says that this system can be safely recovered into the R-134a recovery machine. Technician B says this system has likely been retrofitted using nonstandard procedures. Who is correct?
B Only
A vehicle is being evacuated after an A/C repair but the system will not drop below 10 in Hg after 20 minutes. Technician A says that this is normal and to vacuum for 10 more minutes. Technician B says there is likely a leak in the refrigerant system. Who is correct?
B Only
A vehicle with automatic temperature control (ATC) has a "no bus" message on the control head. Technician A says that the A/C fuse is likely blown and is causing this message. Technician B says that the HVAC system may move to defrost position with heated air from the duct. Who is correct?
B Only
A vehicle with automatic temperature control (ATC) is malfunctioning. A scan tool is connected and a code is retrieved from the system concerning the cabin temperature sensor. Technician A says that the sensor is located near the engine air filter. Technician B says the sensor can be checked with an ohmmeter to see if it has the correct resistance. Who is correct?
B Only
An A/C system that has been worked on at another shop is being diagnosed. It is suspected that refrigerant containing "stop leak" has been added to the system. Technician A says that the refrigerant identifier will detect this substance. Technician B says that this substance can damage A/C recovery/recharging machines. Who is correct?
B Only
An R134a A/C system is being recharged. Technician A says that an A/C system can be accurately charged by monitoring pressure and temperature. Technician B says that the A/C system should be treated with refrigerant dye any time that work has been performed so that future leak testing will be possible. Who is correct?
B Only
Technician A says that a restricted cabin air filter will cause reduced fuel economy. Technician B says that a cabin air filter prevents foreign debris from getting in the evaporator core. Who is correct?
B Only
Technician A says that an electronic blend door motor uses an analog signal to open and close. Technician B says that an electronic mode door motor uses a feedback device to indicate the position of the door. Who is right?
B Only
Technician A says that the line exiting the condenser should be hotter than the line entering the condenser. Technician B says that the suction line should be cold to the touch when the A/C system is operating. Who is correct?
B Only
Technician A says that the suction line should be hot to the touch while the A/C system is operating. Technician B says that the liquid line should be hot to the touch while the system is operating. Who is correct?
B Only
The HVAC fuse blows each time the A/C switch is turned on. Technician A says that an open low side switch could be the cause. Technician B says that a shorted A/C clutch relay coil could be the cause. Who is correct?
B Only
The air gap on a compressor clutch is found to be twice the specified amount. Technician A says this could cause an intermittent scraping noise with the engine running and the compressor clutch disengaged. Technician B says this could cause a slipping compressor clutch when the compressor is engaged. Who is correct?
B Only
The thermal limiter is being diagnosed on a late model vehicle. Technician A says that this device can be checked with a scan tool by using a function test of the cooling fan. Technician B says that this device can be checked with an ohmmeter when the power is turned off. Who is correct?
B Only
The vacuum check valve was missing from the HVAC vacuum circuit but the remaining hoses were still connected. Technician A says that the modes would be stuck in the heat mode and not move in any other positions. Technician B says that the mode actuators would work normally until the vehicle drove up steep hills. Who is correct?
B Only
The vacuum supply hose has been broken at the vacuum check valve. Technician A says that the temperature door will be stuck in the full hot position. Technician B says the defrost door will be stuck in the defrost position. Who is correct?
B Only
A refillable A/C refrigerant cylinder is considered full when it reaches what capacity by weight? A. 50 percent B. 60 percent C. 70 percent D. 80 percent
B. 60 percent
While testing a compressor clutch, a fused jumper wire is used to bypass the load side of the A/C clutch relay. This does not cause the compressor clutch to engage. The LEASR LIKELY cause of this would be: A. An open compressor clutch coil B. A shorted compressor clutch coil C. An open compressor clutch coil ground circuit D. An open relay power feed circuit
B. A shorted compressor clutch coil
What would be the most likely result of a missing A/C compressor clutch diode? A. Inoperative A/C compressor B. Damage to the ECM C. Compressor will not disengage D. Rear defogger will not engage
B. Damage to the ECM
Before replacing an HVAC electronic control panel, the technician should: A. Remove the control cables from the vehicle B. Disconnect the negative battery cable C. Disassemble the dash panel D. Apply dielectric grease to the switch contacts
B. Disconnect the negative battery cable
What is the LEAST LIKELY condition that could cause a blower resistor thermal element to burn up? A. Tight blower motor bearing B. Open blower motor winding C. Wire rubbing a metal bracket D. Blower motor fan blade rubbing the duct
B. Open blower motor winding
What happens to the A/C system during the evacuation process? A. The refrigerant is removed from the A/C system B. The A/C system is pulled into a deep vacuum to remove any moisture C. The refrigerant is filtered and clean D. The refrigerant oil is removed from the A/C system
B. The A/C system is pulled into a deep vacuum to remove any moisture
An air distribution vacuum actuator circuit is being tested using a vacuum gauge. The gauge is connected into the vacuum line going to the engine, and a zero vacuum reading is displayed. This would indicate: A. The HVAC vacuum switching valve is faulty B. The line to the engine is plugged, disconnected, or kinked C. The vacuum actuator is defective D. The actuator should be operational
B. The line to the engine is plugged, disconnected, or kinked
Which device is used as the input to cause the A/C clutch to disengage under heavy engine loads? A. Coolant temperature sensor B. Throttle position sensor C. Oxygen sensor D. Power steering switch
B. Throttle position sensor
Any of these methods are used to move the temperature door EXCEPT: A. Electronic actuators B. Vacuum actuators C. Cables D. Linkages
B. Vacuum actuators
A cycling clutch orifice tube (CCOT) A/C system is operating at 82°F (27.8°C) ambient temperature, the compressor clutch cycles several times per minute, and the suction line is warm. The high side gauge shows lower than normal pressure. The most likely cause of this problem could be: A. A low refrigerant charge B. A flooded evaporator C. A restricted accumulator D. An overcharge of refrigerant
A. A low refrigerant charge
Any of these steps should be followed when replacing an automatic temperature control (ATC) controller EXCEPT: A. Disconnect the positive battery cable B. Connect a ground strap to your wrist and connect to a metallic component C. Use a battery maintainer while reprogramming the new controller D. Disconnect the negative battery cable
A. Disconnect the positive battery cable
Any of these answer choices are a combination of instruments and methods are used to detect an A/C refrigerant leak on an R-134a system EXCEPT: A. Flame type leak detector B. Halogen leak detector C. Dye and UV light D. Audible noise from the leak
A. Flame type leak detector
What is the LEAST LIKELY cause for a heater failing to produce adequate hot air? A. Mode door out of calibration B. Heater core with partially blocked passages C. Heater control valve misadjusted D. Blend air door misadjusted
A. Mode door out of calibration
What function does the A/C clutch coil diode perform for the A/C system? A. Prevents the voltage spike from damaging other components B. Assists the clutch coil in creating magnetism C. Limits current flow to prevent the A/C fuse from overheating D. Connects the clutch coil to ground
A. Prevents the voltage spike from damaging other components
Any more steps should be followed when working around airbag systems EXCEPT: A. Store the airbag components face down in the bench when not in use B. Disconnect the negative battery cable prior to beginning work C. Use caution when reconnecting airbag components D. Walk while holding the airbag comp mental away from the face
A. Store the airbag components face down in the bench when not in use
Vacuum actuators can be used for any of these duct box doors EXCEPT: A. Temperature door B. Defrost mode door C. Fresh air door D. Heat mode door
A. Temperature door
Any of these items need to be checked and inspected when replacing an A/C compressor EXCEPT: A. The piston ring end clearance B. The clutch air gap C. The number of pulley grooves D. The location of the mounting holes
A. The piston ring end clearance
The refrigerant is being recovered from an A/C system. Five minutes after the recovery process is complete, the low side pressure loses the vacuum and the pressure rises above zero. This condition indicates: A. There is still some refrigerant in the system B. There is excessive oil in the refrigerant system C. The refrigerant system is leaking D. There is excessive moisture in the refrigerant system
A. There is still some refrigerant in the system
Any of these components are A/C pressure devices EXCEPT: A. Thermal limiter B. AC pressure transducer C. Dual pressure switch D. Cycling switch
A. Thermal limiter
Which tool should be used to test for problems in a vacuum operated HVAC system? A. Vacuum pump B. Pressure gauge C. Pressure pump D. Vacuum gauge
A. Vacuum pump
A heater core is suspected to be restricted and causing the heater to not be warm enough. Technician A says that a temperature drop test should be performed on the heater inlet and outlet hoses. Technician B says that the heater system should create about 140°F air at the vents. Who is correct?
Both A and B
A knocking noise is heard in the compressor area that is audible when the compressor is engaged but it stops when the compressor turns off. Technician A says that loose compressor mounting bolts could be the cause. Technician B says that a discharge line rubbing a compressor mounting bracket could be the cause. Who is correct?
Both A and B
A knocking sound is heard from the area of the A/C compressor when in operation. When the compressor is shut off, the noise stops. The A/C system cools well, and there are no indications of A/C system problems. Technician A says the noise could be caused by a broken compressor mounting bracket. Technician B says that the noise could be caused by loose fasteners of the compressor mounting. Who is correct?
Both A and B
A pressure switch needs to be replaced on a late model vehicle. Technician A says that the A/C refrigerant does not have to be recovered if the switch has a Schrader valve under it. Technician B says that the refrigerant does need to be recovered if the switch is retained by a snap ring. Who is correct?
Both A and B
A vehicle is being diagnosed for an air conditioning system that cools satisfactorily during the early morning or late evening, but does not cool during the hot part of the day. During the performance, the low side gauge starts out reading normal, then drops into vacuum. Technician A says that ice could be forming in the expansion valve. Technician B says that the drier could be saturated with moisture. Who is correct?
Both A and B
A vehicle is being diagnosed for the problem of the compressor clutch failing to engage with the A/C turned on. A voltage measurement shows there is 12 volts at the clutch coil feed wire. Technician A says that the clutch coil could be bad. Technician B says that the clutch coil ground could be bad. Who is correct?
Both A and B
A vehicle with an automatic temperature control (ATC) system is being diagnosed. Technician A says that the ATC trouble codes can be retrieved by depressing a sequence of buttons on the ATC control head. Technician B says that the trouble code reveals which area needs to be repaired in an ATC system. Who is correct?
Both A and B
A vehicle with rear heat and air has a rear heater that does not get warm enough. Technician A says that a crimped heater pipe could be the cause. Technician B says that a partially blocked rear heater core could be the cause. Who is correct?
Both A and B
All of the vacuum controls are inoperative with the engine running at idle speed. Technician A says that the problem could be caused by a disconnected vacuum supply hose. Technician B says that the manifold vacuum fitting may be blocked. Who is correct?
Both A and B
An airbag system needs to be disarmed during an evaporator core replacement. Technician A says that it is necessary to remove power from the system prior to component removal. Technician B says that the inflatable devices should be laid "face up" in a secure area after being removed from a vehicle. Who is correct?
Both A and B
During a diagnosis of an A/C system, oil residue is found around the high pressure relief valve and the A/C refrigerant charge has been determined to be low. Technician A says the cause could be restricted air passages through the condenser. Technician B says the refrigerant system may have been overcharged. Who is correct?
Both A and B
Ha vehicle with automatic temperature control (ATC) has a problem with the A/C system. The set temperature control and the actual temperature control in the cab is 20 degrees different after 15 minutes of operation. Technician A says the cabin air temperature sensor may be defective. Technician B says the temperature blend door may be sticking. Who is correct?
Both A and B
Technician A says HVAC control panel directs the signal to the mode actuators to determine where the air is discharged. Technician B says that some HVAC control panels contain logic capabilities. Who is correct?
Both A and B
Technician A says that a restricted cabin air filter can cause reduced airflow at all of the duct outlet locations. Technician B says that the cabin air filter should be inspected during routine preventative maintenance activities on a vehicle. Who is correct?
Both A and B
Technician A says that all A/C repair shops are required to use SAE approved recovery equipment. Technician B says that all individuals who service A/C systems must be certified by a recognized body on how to properly handle refrigerants. Who is correct?
Both A and B
Technician A says that an overheating engine can cause the A/C to shut down and blow warm air. Technician B says that running the vehicle at wide open throttle for several miles can cause the A/C to lose performance. Who is correct?
Both A and B
Technician A says that electronic mode actuators can be recalibrated by using a scan tool. Technician B says that electronic blend actuators can be recalibrated by using a scan tool. Who is correct?
Both A and B
Technician A says that the evaporator temperature switch is a thermostatic device that opens when the evaporator core gets near the freezing level. Technician B says that the evaporator temperature sensor is a thermistor that varies the temperature changes in the evaporator core. Who is correct?
Both A and B
Technician A says that the scan tool receives data from the vehicle by communicating on the data bus network. Technician B says that if one of the two data bus wires becomes broken, then the network can still communicate on the remaining good wire but will set a trouble code. Who is correct?
Both A and B
The A/C compressor will not engage when the A/C is turned on. The static refrigerant pressure is 75 psi and the outside air temperature is 72°F. Technician A says that a poor connection at the pressure cycling switch could be the cause. Technician B says that a faulty A/C clutch coil could be the cause. Who is correct?
Both A and B
The receiver/drier is being replaced on a late model vehicle. Technician A says that the drier should be installed last to prevent it being exposed to moisture for a prolonged time. Technician B says that some refrigerant oil should be added to the drier prior to installation. Who is correct?
Both A and B
An A/C system has just been recovered with a multipurpose recovery/recharging machine. Which of these statements is true of the condition of the A/C system? A. All of the oil has been removed from the system B. The system is ready for normal use C. All refrigerant has been removed from the system D. Humidity has been removed from the refrigerant in the system
C. All refrigerant has been removed from the system
What is the most likely cause for a blower motor fuse to blow? A. Blower resistor open B. Faulty blower motor ground circuit C. Blower motor seized D. Burned blower relay contact
C. Blower motor seized
Any of these practices should be followed when interacting with airbag system components EXCEPT: A. Unhook the negative battery cable prior to beginning work B. Store inflatable components "face up" in a secure area C. Disconnect the airbag indicator prior to beginning work D. Carefully carry inflatable components holding them away from the body
C. Disconnect the airbag indicator prior to beginning work
A vehicle is in the shop for an overheating problem. During the inspection the technician finds that the upper radiator hose collapses after the engine cools down but moves back to normal when the radiator cap is removed. The most likely cause for this problem is? A. Faulty water pump B. Malfunctioning cooling fan C. Faulty radiator cap D. Faulty thermostat
C. Faulty radiator cap
An A/C compressor is noisy when the clutch is engaged but the noise stops when the clutch is disengaged. Which of these is the most likely cause? A. Faulty compressor clutch pulley bearing B. Low refrigerant charge C. Internal compressor damage D. Overtightened drive belt
C. Internal compressor damage
Any of these are acceptable results from an A/C performance test EXCEPT: A. Duct temperature ranging from 40°F to 50°F (4.4°C-10°C) B. High side pressure at approximately two to three times the ambient temperature C. Low side pressure at approximately 50 to 70 psi (343.8kPa to 482.6kPa) D. Suction line is cold to the touch
C. Low side pressure at approximately 50 to 70 psi (343.8kPa to 482.6kPa)
Any of these conditions can cause elevated high side pressures EXCEPT: A. Refrigerant overcharge B. Restricted airflow to the condenser C. Poor airflow across the evaporator D. A slipping fan clutch
C. Poor airflow across the evaporator
What is the most likely cause for a serpentine drive belt to slip under heavy loads? A. Surface cracks on the inside of the belt B. Belt is stretched one quarter inch C. Seized tensioner D. Glazed belt
C. Seized tensioner
The most likely problem that would result from an open blower resistor would be: A. The blower would work on all lower speeds but not on high speed B. The blower would not work on any speed C. The blower would only work on high speed D. The blower fuse would blow each time the blower is turned on at any speed
C. The blower would only work on high speed
The high side pressure on a system with a cycling clutch and pressure cycling switch is 245 psi, the low side pressure hovers around 28 psi, and the ambient temperature is 98°F. What do these gauge readings indicate? A. The system is undercharged B. The system is overcharged C. The system is normal D. The evaporator pressure regulator is bad
C. The system is normal
A vehicle has the temperature selector set to the cool position but the air from the vents is warm. The most likely problem is: A. The engine cooling fan is inoperative B. The engine coolant level is low C. The heater cores coolant passages are restricted D. An air blend door is stuck
D. An air blend door is stuck
The windshield fogs up when the defroster is turned on and the cab is filled with a sweet smell. Which of these is most likely cause? A. Blown head gasket B. Leaking heater control valve C. Leaking evaporator core D. Leaking heater core
D. Leaking heater core
An orifice tube performs any of these jobs in the A/C system EXCEPT: A. Meters refrigerant into the evaporator core B. Filters foreign particles C. Separates the high side from the low side D. Opens and closes to regulate pressure on the low side
D. Opens and closes to regulate pressure on the low side
Which of these equipment is the most likely way to detect dealer in an A/C refrigerant system? A. Recovery machine B. Vacuum pump C. Manifold set D. Orifice bleed detection kit
D. Orifice bleed detection kit
Which of these oils is the standard oil used by OEMs in (nonhybrid) R134a systems? A. Mineral oil B. 10A30 C. Ester oil D. Polyalkylene glycol (PAG)
D. Polyalkylene glycol (PAG)
Any of these methods of R134a A/C system leak detection are acceptable EXCEPT: A. Dye and black light B. Electronic leak detector C. Nitrogen and soapy water D. Propane burner
D. Propane burner
A vehicle with an R-134a A/C system is being leaked tested. Which of these methods is the LEAST LIKELY method to find a refrigerant leak? A. Visual inspection B. Electronic detector C. Nitrogen injection D. Propane injection
D. Propane injection
The purpose of the A/C presser sensor is to: A. Open and close as refrigerant pressure changes in the low side of the system B. Open and close as refrigerator pressure changes in the high side of the system C. Send variable signal to a processor as evaporator temperature changes D. Send a variable signal to a processor as high side pressure changes
D. Send a variable signal to a processor as high side pressure changes
The compressor clutch will not disengage when the A/C control is switched to off. The most likely problem is: A. The A/C pressure cutoff switch is stuck open B. The compressor clutch coil is shorter to ground C. The low pressure switch has an open wire D. The compressor coil feed circuit is shorted to voltage
D. The compressor coil feed circuit is shorted to voltage
Any of these methods to verify that the evaporator core is leaking EXCEPT: A. Using an electronic leak detector at the A/C duct outlets B. Using an ultrasonic leak detector at the HVAC case drain tube C. Injecting dye into the system and using a black light to inspect the substance exiting the HVAC case drain tube D. Using a refrigerant identifier at the low side fitting
D. Using a refrigerant identifier at the low side fitting
A condenser is being diagnosed for an airflow problem. Technician A says a slipping fan clutch will reduce ram airflow. Technician B says reduced airflow across the condenser results in low suction pressure. Who is correct?
Neither A or B
A performance test is being performed on the A/C system. Technician A says that the A/C system should be turned on normal A/C and the blower set to low speed. Technician B says that the engine should be at idle during this test. Who is correct?
Neither A or B
A vehicle A/C system is being recharged manually with a manifold set and a 30 pound cylinder of refrigerant. Technician A says that the high side manifold valve should be open when charging with the system turned on. Technician B says that the low side manifold valve should be closed when charging with the system turned on. Who is correct?
Neither A or B
An R-134a A/C system has a damaged service fitting. Technician A says the fitting needs to be mid seated after the manifold hose adapter is installed in order to read A/C pressure. Technician B says that the Schrader valve in the fitting can be replaced without recovering the refrigerant. Who is correct?
Neither A or B
Technician A says a restricted orifice tube will cause elevated pressures on the low and high sides of the A/C system. Technician B says that faulty reed valves in the compressor can cause elevated pressures on the low and high side of the A/C system. Who is correct?
Neither A or B
Technician A says that R-134a systems use mineral oil to lubricate the compressor. Technician B says that R-12 systems use PAG oil to lubricate the compressor. Who is correct?
Neither A or B
Technician A says that stored refrigerant should be kept warm by providing a heat source near the storage area. Technician B says that recovered refrigerant should be kept in a DOT 39 cylinder. Who is correct?
Neither A or B
Technician A says that the service fittings for R-134a are the same as R-12 service fittings. Technician B says that the low side service fittings is a 16mm quick connect style and the high side fitting is a 13mm quick connect style. Who is correct?
Neither A or B
The A/C system refrigerant charge amount needs to be determined on a late model vehicle. Technician A says that the emissions label contains the refrigerant charge amount. Technician B says that the RPO decal contains the refrigerant charge amount. Who is correct?
Neither A or B
