ASE A7 EXAM 1

A. (when the suction line in hot = low refrigerant. when its frosted = theres a restriction in the lines. overcharged refrigerant = high pressure is higher than normal))

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 pressures. 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

D. (A/C should be max cold and blower on high. rpm should be 1500)

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? A. A only B. B only C. Both A and B D. Neither A nor B

B. (look back)

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

A.

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. A only B. B only C. Both A and B D. Neither A nor B

A.

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 air conditioning belt is loose. Who is correct? A. A only B. B only C. Both A and B D. Neither A nor B

A.

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. A only B. B only C. Both A and B D. Neither A nor B

C.

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. A faulty water pump B. A malfunctioning cooling fan C. A faulty radiator cap D. A faulty thermostat

A. (if the control valve was stuck open it would not have a heating issue)

A vehicle is in the shop with the complaint 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. A only B. B only C. Both A and B D. Neither A nor B

A. (pressure sensor are most often mounted somewhere on the high side)

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. A only B. B only C. Both A and B D. Neither A nor B

C.

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? A. A only B. B only C. Both A and B D. Neither A nor B

B.

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? A. A only B. B only C. Both A and B D. Neither A nor B

C.

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? A. A only B. B only C. Both A and B D. Neither A nor B

A. (look back)

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. Technician B says that the pressure release valve is opening the circuit to the compressor clutch. Who is correct? A. A only B. B only C. Both A and B D. Neither A nor B

C. (an internally damaged compressor would make noise only when the compressor is on, then stops when turned off)

An A/C compressor is noisy when the clutch is engaged but the noise goes away 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.

An A/C system is being diagnosed for a leak. Technician A carefully checks all system connections and says the presence of oil around the fitting of an air conditioning line or hose is an indication of a possible refrigerant leak. Technician B uses a handheld electronic leak detector and moves the hose slowly along all components of the refrigerant system. Who is correct? A. A only B. B only C. Both A and B D. Neither A nor B

B.( to accurately charge the a/c system the refrigerant must be weighed )

An R-134a 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? A. A only B. B only C. Both A and B D. Neither A nor B

B.

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.

C.

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? A. A only B. B only C. Both A and B D. Neither A nor B

D. (the orifice tube does not open and close. it is a fixed restriction that meters refrigerant into the evaporator 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

C. (low side pressure should be 25 to 35psi during performance test)

Any of these are acceptable results from an A/C performance test EXCEPT: A. Duct temperatures 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 D. Suction line is cold to the touch

D. (A refrigerant identifier is used to test the A/C system for impurities)

Any of these are 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

C. (would cause poor air flow to the ducts)

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

B.

Any of these methods are used to move the temperature door EXCEPT: A. Electronic actuators B. Vacuum actuators C. Cables D. Linkages

D.

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

C.

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. (suction lines are cold to the touch when the system is operating)

Any of these statements about refrigerant lines are true EXCEPT: A. Suction lines are located between the outlet side of the evaporator and the inlet side or suction side of the compressor. B. Suction lines carry the low-pressure, low-temperature refrigerant vapor to the compressor where it again is moved through the system. C. Suction lines can be distinguished from the discharge lines by touch: They are hot to the touch when the system is operating. D. The suction line is larger in an meer tant the liquid line because refrigerant in a vapor state takes up more room than refrigerant in a liquid state.

B.

In the figure above, the blower motor only works on high speed. Technician A says that a faulty ground at the blower switch could be the cause. Technician B says that an open blower resistor could be the cause. Who is correct? A. A only B. B only C. Both A and B D. Neither A nor B

A.

Referring to the figure above, Technician A says that the old compressor oil should be drained and measured when replacing an A/C compressor. Technician B says that the old oil should be added to the new compressor. Who is correct? A. A only B. B only C. Both A and B D. Neither A nor B

D. (double check this)

Referring to the figure above, list the correct flow of refrigerant from the compressor exit point back to the compressor inlet point. A. A to C to B to E to F to D B. D to A to C to B to E to F C. B to C to A to D to F to E D. D to F to E to B to C to A

B.

Referring to the figure above, the mode door actuator is inoperative. Technician A says that the computer senses the position of the mode door by monitoring the reference voltage. Technician B says that the computer provides the ground for the mode door position switch. Who is correct? A. A only B. B only C. Both A and B D. Neither A nor B

A. (a restricted orifice tube would cause the low side pressure to be lower than normal and reduce cooling performance)

Technician A says a restricted orifice tube could be caused by debris from a failing compressor. Technician B says an orifice tube restriction would cause a low-side pressure that is considerably higher than specified. Who is correct? A. A only B. B only C. Both A and B D. Neither A nor B

B. (Electronic blend door motors use some sort of feedback device. A potentiometer is typically used to signal the HVAC control device the correct door position)

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? A. A only B. B only C. Both A and B D. Neither A nor B

C. (look back)

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 as the temperature changes in the evaporator core. Who is correct? A. A only B. B only C. Both A and B D. Neither A nor B

C.

Technician A says the desiccant in a receiver/drier absorbs moisture and it can become quickly contaminated if exposed to atmosphere. Technician B says orifice tube systems use an accumulator to store excess refrigerant and to filter and dry the refrigerant. Who is correct? A. A only B. B only C. Both A and B D. Neither A nor B

B. (a stuck closed a/c compressor control relay would cause it to stay on)

The A/C clutch in the figure above will not engage. Which of these would be the LEAST LIKELY cause? A. A blown fuse 17 B. A stuck closed A/C compressor control relay C. A faulty PCM relay driver D. A faulty pressure cycling switch

C. (look back)

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? A. A only B. B only C. Both A and B D. Neither A nor B

B.

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? A. A only B. B only C. Both A and B D. Neither A nor B

C.

The fins and air passages of an evaporator are heavily clogged and the airflow has been greatly reduced. Technician A says the evaporator core must be removed from the case for proper cleaning. Technician B says this condition can cause extra load on the blower motor. Who is correct? A. A only B. B only C. Both A and B D. Neither A nor B

A.

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 the problem could be an inoperative cooling fan. Who is right? A. A only B. B only C. Both A and B D. Neither A nor B

C. (look back)

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 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.

A. (if the low side gauge rises above zero after a short period, there is likely still refrigerant present in the a/c system)

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.

B. (the thermal limiter is an inline thermal circuit protection device that can be tested with an ohmmeter with the circuit turned off. a scan tool cannot check this device with the function test of the cooling fan)

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? A. A only B. B only C. Both A and B D. Neither A nor B

B. (if vacuum is lost, most HVAC systems will default to the defrost setting by design)

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? A. A only B. B only C. Both A and B D. Neither A nor B

A.

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.

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

C.

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

B.

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

D.

Which of these oils is the standard oil used by OEMs in (nonhybrid) R-134a systems? A. Mineral oil B. 10W30 C. Ester oil D. Polyalkylene glycol (PAG)

B.

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 LEAST 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