ASE A7 Heating & Air Conditioning Copy

This question has the word EXCEPT. For this question, look for the choice that could NOT cause the described situation. Read the entire question carefully before choosing your answer. All of the following are true regarding the expansion valve, EXCEPT:

The A/C compressor clutch does not engage. Technician A says that an open high pressure cutout switch could be the problem. Technician B says a blown compressor clutch diode could be the cause. Which technician is correct?

When trying to diagnose a vehicle A/C systems poor performance when the vehicles engine runs perfectly it is observed that a yellow liquid is leaking from the evaporator. What kind of fluid is leaking?

If the air conditioning system has an accumulator, it is a:

An EATC air conditioning system has low fan speed operation during high demand situations, like in direct sunlight. Technician A says this is because something is covering the sun load sensor’s photo diode. Technician B says a sun load sensor is a variable resistor and can be tested with an ohmmeter. Who is correct?

An A/C compressor has a growling noise only with the compressor clutch engaged. The cause of this noise could be:

During normal operation, the receiver-drier on a TXV system should feel:

Technician A says all air conditioning connections use a gasket or O-ring to seal the system. Technician B says when replacing O-rings you lubricate the O-ring with the correct refrigerant oil to prevent nicks and ease installation. Who is right?

Two technicians are discussing the air-conditioning control circuit shown. Technician A says that the computer (ECM) controls the operation of the compressor clutch. Technician B says that the compressor clutch will not engage if the refrigerant pressure is below 8 psi or higher than 430 psi. Which technician is correct

Which of the following is an expansion device?

A gurgling sound is heard coming from inside the dashboard of a vehicle. Technician A says this is air trapped in the heater core. Technician B says this noise can be caused by a blown head gasket. Who is correct?

On a vehicle with V-belts, an intermittent squealing noise is heard on acceleration with the A/C control switch in the on or off position. The most likely cause of this problem is:

When a compressor clutch first engages it squeals. This is probably caused by _____. Option A says This is being caused by a bearing in the clutch pulley. Option B This is being caused by a worn out or loose serpentine belt. Which is correct?

If the floor of the front passenger side is wet, this could be caused by a _____

A concern of intermittent AC cooling is being diagnosed. The gauge set shows intermittently high and low side pressure gauge readings and the high side intermittently drops to 100 psi. Which of the following is the MOST likely cause?

When replacing an A/C compressor, the refrigerant system is discharged and 2 oz. (59 mL) of oil is recovered from the system. When the old compressor is removed, 2 oz. (59 mL) of oil is drained from the compressor. The amount of oil drained from the new compressor is 6 oz. (177.4 mL). When the new compressor is installed, the amount of oil added to the compressor should be:

A manifold gauge indicates a system has low discharge pressure. The MOST likely cause of this condition is:

In a fixed orifice tube air conditioning system, the Orifice Tube is located between the ____ and ____.

The most likely cause of the A/C making a honking noise while operating would be:

A lack of cooling is being diagnosed. A technician discovers that the high-pressure line is hot to the touch on both sides of the orifice tube. Technician A says that is normal operation for an orifice tube system. Technician B says that the orifice tube may be clogged. Which technician is correct?

The fact that a cycling clutch compressor runs for only a short time, then turns off is most likely caused by:

Which of the following statements is not true:

What high-side and low-side pressure gauge readings would a technician find if the condenser fan were inoperative?

A gurgling sound from the radiator could mean:

The owner of a vehicle equipped with an orifice tube-type air conditioning system complains that the inside of the vehicle does not cool properly. The air conditioning compressor clutch constantly cycles on and off whenever the air conditioning is on. Technician A says that the system is likely low on refrigerant. Technician B says that the most likely cause is an electrical short in the wiring to the air conditioning compressor clutch. Which technician is correct?

A CCOT system has a high high side. Technician A says to suspect the thermostatic expansion valve. Technician B says this system contains an orifice tube. Who is correct?

An A/C system blows cool air when the vehicle is started with an ambient temperature of 80 deg F (26.7 deg C). After the vehicle is driven for about 10 mi. (16 km), the system stops blowing cool air,a nd the thermal expansion valve (TXV) is frosted. When the A/C system is shut off for five minutes and turned on again, it blows cool air for another 10 mi. (16 km). The most likely cause of this problem is:

The compressor is rapidly cycling on and off on a CCOT air conditioning system. Technician A says this condition can be caused by a low refrigerant charge. Technician B says this could be caused by a faulty clutch cycling switch. Who is correct?

Technician A says while performing a retrofit from R-12 refrigerant to R134a refrigerant, the refrigerant must be recovered into a dedicated cylinder, they cannot be mixed. Technician B says R-12 refrigerant functions at higher pressures than R-134a refrigerant does. Who is correct?

Technician A says, discharging an A/C system slowly minimizes oil loss. Technician B says, servicing an air conditioner involves discharging and evacuating the system until it holds a steady vacuum. Who is right?

During an initial inspection, the technician notices that one line on the receiver drier is cooler than the other. This is caused by:

Which of the following conditions is the MOST likely cause of a vehicle overheating?

All of the following statements about an A/C evaporator are true except:

An A/C compressor high-pressure release valve discharges refrigerant at approximately:

What two items must be installed or replaced when retrofitting a CFC-12 system to an HFC-134a system?

If an A/C system with a variable displacement compressor is weak under high cooling modes, which of the following would typically not be the cause?

If a cooling system operates at too cool an operating temperature, the engine will do which of the following?

Two technicians are discussing refrigerant storage. Technician A says HFC-134a is contained in a sky blue container. Technician B says CFC-12 is contained in a white container. Who is correct?

An air conditioning performance test is being performed. All of the following should be done except:

Two technicians are discussing an inoperative electric blend door in an automatic air conditioning system. Technician A says to inspect the blend door’s wiring and connections for an open circuit. Technician B says to troubleshoot this circuit with a test light. Who is correct?

A customer complains about engine coolant loss. The cooling system is pressurized at 15 psi (103 kPa) for 15 minutes. There is no visible sign of coolant leaks in the engine or passanger compartments, but the pressure on the tester gauge decreases to 5 psi (34 kPa). This problem could be caused by any of the following defects EXCEPT:

During a visual inspection an oily spot is found on a hose leading from the compressor. Technician A says there may be a refrigerant leak in the system. Technician B says today’s R134a systems use mineral oil instead of the older R12 compatible PAG oil. Who is correct?

A squeal is heard only when the compressor clutch first engages. Technician A says this is caused by a loose serpentine belt. Technician B says this is caused by a worn clutch pulley bearing. Who is correct?

The vacuum valve in the radiator cap is stuck closed. The result of this problem could be:

Technician A says, Polyalkylene Glycol (PAG) refrigeration oil is used as original equipment on R-134a systems. Technician B says, store leftover PAG oil in a tightly sealed metal container for later use. Who is right?

During the test for noncondensable gases in recycled R-12, the refrigerant must be:

If a suction line leading to the compressor from the thermostatic expansion valve is cool to the touch this would indicate.

An air conditioning system contains a thermostatic expansion valve. The suction line leading to the compressor is cool to the touch. This indicates:

An engine runs normally until the air conditioning is engaged. Then it idles roughly and occasionally stalls. What is the most likely cause?

All of these are true about an accumulator EXCEPT:

In a vehicle that might have a faulty in-cabin temperature control sensor, which of the below statements is true?

Technician A says, a condenser corroded from acids formed by water contamination can be serviced by backflushing. Technician B says, a chemical flush can be used to clean a corroded condenser. Who is right?

All these statements are true about a throttle position sensor EXCEPT:

A strong pungent odor comes out of the air-conditioning vents. Technician A says that mouthwash should be poured into the air inlet near the windshield to stop the odor. Technician B says that fungicide should be sprayed onto the evaporator to stop the odor. Which technician is correct?

A frozen spot is noticed in the center of the condenser. Technician A says a frozen spot on a component or connection indicates a restriction in the system. Technician B says this is caused by a clogged orifice tube. Who is correct?

This question has the word EXCEPT. For this question, look for the choice that could NOT fit the described situation. Read the entire question carefully before choosing your answer. All of the following statements are correct regarding an air conditioning performance test, EXCEPT:

A port-fuel-injected engine has an excessively rich air:fuel ratio. This problem could be caused by:

All of the following statements about cooling system service are true EXCEPT:

During an air conditioning performance test, the technician notices that the compressor outlet is hot. Technician A says this is a normal condition. Technician B says the air conditioning system is overcharged. Who is right?

Technician A says that the air-conditioning compressor should operate when the controls are set to the heat position. Technician B says the air-conditioning compressor should operate when the controls are set to the defrost position. Which technician is correct?

Which of the following statements are true?

A technician is diagnosing a vehicle’s air conditioning system. The vehicle has good engine performance, but the air conditioner is blowing warm air only. A yellow substance is noticed around the evaporator case drip tube. Technician A says this is coolant leaking from the heater core. Technician B says this is fluorescent dye leaking from the evaporator core. Which technician is MOST likely correct?

Technician A says, under normal operating conditions the line leading from the condenser to the expansion device on an A/C system should feel cold. Technician B says, a restriction in the A/C system low-side causes the line to feel cold. Who is right?

On a very humid day, you can expect A/C system pressures to be:

A manifold pressure gauge set is ____.

Technician A says, if the heat level does not change when the temperature selector is moved on a vacuum-operated heating system the vacuum motor linkage may be disconnected. Technician B says, no heat level change when the temperature selector is moved can be caused be a heater control valve malfunction. Who is right?

All of the following statements are correct EXCEPT:

Technician A says, an A/C system with a low refrigerant level can cause low gauge readings on both the high-side and low-side. Technician B says, a defective expansion valve can cause a very low low-side pressure and normal to slightly low high-side pressure. Who is right?

All of the following statements about computer-controlled A/C system actuator motors are true EXCEPT:

A condenser is being flushed. Technician A says that the old refrigerant oil can be mixed with and disposed of with used engine oil. Technician B says that refrigerant oil should be added to the new condenser in R-134a systems. Which technician is correct?

Technician A says when the condenser airflow is restricted the pressure is high in both high and low lines. Technician B says an indication of low refrigerant is when both the high and low sides show low pressure. Who is right?

All of the following statements about A/C-heater control panel service are true EXCEPT:

R 134a Refrigerant:

A typical control panel assembly controls all of the following EXCEPT the:

The recirculate door is inoperable. Any of the following may be the problem EXCEPT a:

The compressor clutch will not disengage. The problem could be that:

Two technicians are discussing electric cooling fans and air conditioning performance. Technician A says electric fans regulate refrigerant temperatures more precisely than belt driven fans do. Technician B says electric cooling fans are controlled by control modules that use temperature and pressure actuated sensors and switches. Who is correct?

When filling an A/C system recovery container with recovered refrigerant, the percentage of capacity that the container may be filled to is

This question has the word EXCEPT. For this question, look for the choice that could NOT fit the described situation. Read the entire question carefully before choosing your answer. All of the following tasks are performed when replacing an AC compressor, EXCEPT:

Technician A says, if there is no pressure drop for three minutes during a heater core pressure test, the heater core is not leaking. Technician B says, the heater core is not contaminated with sediment if there is no pressure drop after three minutes. Who is right?

If a vehicle is thought to have both R12 and R134a refrigerants mixed together in the system, the system should:

The most likely cause of a heating system delivering too much heat to the passenger compartment would be:

To locate the source of a foul odor whenever the A/C system is operating, inspect the:

A noisy compressor is being discussed. Technician A says that the air-conditioning system could be low on lubricating oil. Technician B says that the system could be overcharged. Which technician is correct?

When checking a refrigerant container for noncondensable gases:

If an automobiles A/C system cools less at traffic light and going slow then it does at high speeds like on the freeway, what could be the reason for this?

If the two lines on the receiver drier are different temperatures, this could be cause by _____.

All of the following statements about A/C recovery/recycling equipment are true EXCEPT:

A compressor clutch will not engage. Power and ground at the clutch coil are good. Which of the following is the MOST likely cause?

An automotive air-conditioning refrigerant system has been disconnected for several months and is now being returned to service. Technician A says that the receiver drier or accumulator should be replaced. Technician B says the system should be flushed and fresh refrigerant oil should be installed before evacuating and recharging the system. Which technician is correct?

The most likely cause of low discharge pressure on a manifold gauge is _____.

After the recovery process, the low-side pressure increases above zero after five minutes. This condition indicates:

Which of the following oils can be used in a R-134a system?

Which of the following is not recommended while converting an R-12 system to R-134a?

On a manual air conditioning system without automatic control, the compressor clutch does not operate. Technician A says there is a failed compressor thermal protector. Technician B says there is an incorrectly adjusted temperature door. Who is right?

The moisture warning light on the recovery/recycling equipment indicates yellow during the recycling process. This indicates:

After the water pump was replaced and the cooling system refilled with coolant, the heater stopped providing hot air. Which is the most likely cause?

In reference to refrigerant storage, HFC-134a is contained in a ____ container and CFC-12 is contained in a _____ container.

To charge an air conditioning system while it is running, the refrigerant should be added to:

Using a DMM (digital multimeter), a technician measures 12 volts at the clutch coil, but it will not engage. Technician A says a bad clutch coil could be the cause. Technician B says a bad clutch coil ground could be the cause. Who is right?

Technician A says that the air conditioning compressor clutch may not engage if the steering wheel is being turned sharply and the vehicle is equipped with power steering. Technician B says that the air conditioning compressor clutch may not engage if the refrigerant system is low on charge. Which technician is correct?

A reduced amount of airflow from the air conditioning vents is being discussed. Technician A says that the evaporator could be clogged as a result of a small refrigerant leak causing oil to trap and hold dirt. Technician B says that the blower motor ground connection could have excessive voltage drop. Which technician is correct?

This question has the word EXCEPT. For this question, look for the choice that could NOT fit the described situation. Read the entire question carefully before choosing your answer. All of the following issues regarding a receiver/dryer are correct, EXCEPT: