ASE A7 Practice Test.
Free practice exam — 61 verified questions, instant feedback.

Answer: C
Many resistor assemblies include a thermal-protection element that opens the circuit once the resistor overheats from sustained current draw, then resets once the assembly cools, producing exactly this pattern of intermittent failure tied to run time and temperature. A wiring short would not clear itself after cooling, and neither the engine thermostat nor a refrigerant pressure switch has any connection to blower motor operation.

Answer: B
A heater control valve that stays closed blocks hot coolant from circulating through the heater core, so the core inlet hose stays only lukewarm even though the engine itself reaches normal operating temperature and does not overheat. A radiator cap issue would show up as cooling system pressure problems or boil-over, a clogged cabin filter reduces airflow volume rather than its temperature, and a condenser problem has no effect on the heating side of the system.

Answer: B
A thermostat stuck closed blocks coolant from reaching the radiator at all, so the engine's own heat has nowhere to go and the temperature rises quickly while the upper hose feeding the radiator stays cool because no hot coolant is circulating through it. A heater core leak or weak radiator cap would not cause this rapid a temperature rise with a cool upper hose, and a collapsed lower hose typically causes overheating that develops gradually under load, not immediately from a cold start.

Answer: B
A thermostat stuck open allows coolant to continuously circulate through the radiator even when the engine is cold, preventing the engine from reaching and holding its normal operating temperature, which explains the slow warm-up, weak heater output, and the fuel economy penalty from the engine control system compensating for a cooler-than-expected engine. A fan running constantly or a locked fan clutch would create excess airflow through the radiator but would not by itself prevent coolant flow, and a clogged cabin filter only restricts airflow volume, not temperature.

Answer: C
On a vehicle equipped with an electric cooling fan, the fan is switched on by a relay that is commanded by a temperature signal, so a fan that never activates even at elevated temperatures points directly to a fault in that relay or its control circuit rather than a mechanical fan component. A viscous fan clutch applies only to belt-driven fans and is not present on an electric-fan system, a heater control valve affects cabin heat rather than radiator cooling, and a radiator cap issue would cause coolant loss rather than a fan that never runs.

Answer: D
A water pump has an internal bearing and shaft seal; as the bearing wears it produces a growling noise that tracks engine speed, and coolant weeping past the worn seal drains through the pump's weep hole and stains the housing below it, matching both symptoms together. A radiator cap or thermostat fault would not produce a bearing-type noise, and a clogged heater core would reduce cabin heat rather than cause a leak and noise at the front of the engine.

Answer: D
Air pockets trapped in the cooling system after a repair can migrate through the heater core and momentarily displace coolant flow, causing the heater to blow intermittently cool until the air works its way out or rises to the highest point in the system; the recovery tank can still look full even while air remains trapped elsewhere in the loop. A stuck thermostat or condenser fault would produce a steady problem rather than an intermittent one tied to recent service, and an ambient sensor affects automatic climate calculations, not the physical coolant flow through the core.

Answer: D
The lower radiator hose is on the suction side of the water pump, so a hose that has lost its internal spring support or has deteriorated can collapse under the vacuum created by pump speed increasing with engine rpm, temporarily restricting coolant flow and allowing temperature to creep up at higher speeds. A fan clutch problem or cabin filter clog would not cause a hose to visibly collapse, and a heater control valve issue affects cabin heat rather than the shape of the radiator hose.

Answer: D
Vacuum-actuated mode doors are commonly designed to fail safe to the defrost position when vacuum is lost, since that keeps the windshield clear even during a system fault; no vacuum at the actuator diaphragm confirms a leak or lost vacuum source rather than an electrical or refrigerant issue. A blower resistor fault would affect fan speed rather than mode door position, and an overcharged system or clutch coil fault relates to the refrigeration side, which has no connection to vacuum-operated air doors.

Answer: D
Since manually moving the linkage at the actuator does redirect airflow to the other outlets, the doors themselves and the ductwork are functioning correctly, which points to a broken or disconnected linkage between the actuator and the door as the reason the actuator's movement is not being transferred to the door when commanded from the control head. A clogged evaporator would restrict airflow generally rather than lock it to one outlet, and a low-pressure switch or blower resistor fault has no bearing on which outlet air exits from.

Answer: D
A coolant level that is chronically low, likely from a small leak elsewhere in the system, allows air to be drawn into the heater core especially during hard cornering or braking when coolant sloshes in the reservoir, causing fluctuating heat output; topping off temporarily masks the symptom until the level drops again. A condenser fan or recirculation door issue affects the air conditioning and outside-air intake, not heater warmth, and an in-vehicle sensor affects automatic climate calculation rather than the physical presence of air in the heater core.

Answer: A
Plastic radiator end tanks expand slightly as they heat up and come under system pressure, which can open a hairline crack just enough to leak, and the same tank contracts and effectively reseals the crack once the engine cools down and pressure drops, producing a leak that only appears when hot and disappears when cold. A radiator cap releasing pressure would show as overflow tank loss rather than a leak specific to a tank crack, and neither the water pump nor the thermostat directly changes plastic tank dimensions or would cause a leak that opens and closes with temperature in this way.

Answer: A
When every physical indicator of engine temperature, including hose warmth and the absence of coolant loss or performance symptoms, points to a normally operating cooling system, a gauge reading at the hot end most likely reflects a fault in the sender itself or in the wiring feeding the gauge rather than an actual overheating condition. A stuck thermostat, worn pump, or clogged radiator would each produce real symptoms such as a cool hose, coolant loss, or reduced cooling performance, none of which are present here.

Answer: A
Moisture that condenses on the evaporator core during normal operation and does not fully drain can support mold and bacterial growth on the core and in the case; the trapped odor is strongest when air first passes over the core at startup and dissipates as fresh airflow clears it out, all while refrigerant charge and airflow volume remain unaffected and test normal. A refrigerant leak would show up as reduced cooling performance and low pressures, a resistor fault would affect blower speed rather than odor, and the engine thermostat has no connection to cabin air odor.

Answer: C
A hot heater core inlet hose confirms that hot coolant is reaching the core and the heating side of the cooling system is functioning correctly, so cool air at the vents despite a hot core points to the blend door failing to move into position to route air across that core, most likely from a failed or disconnected blend door actuator. A heater control valve stuck closed would prevent the core itself from getting hot, which is not the case here, and a thermostat or radiator cap issue affects overall engine cooling rather than where air is routed inside the HVAC case.

Answer: B
Some intake manifolds route coolant through internal passages sealed by the manifold gasket, so a failing gasket at that location produces exactly the pattern described: a sweet smell and residue under the hood near the manifold with no interior symptoms at all, since the leak never reaches the cabin airflow. A heater core or under-dash hose leak would instead produce cabin odor and window film, and a leaking radiator cap would show residue near the radiator neck rather than at the base of the intake manifold.

Answer: B
Suspending a thermostat in heated water and observing the temperature at which it begins to open, compared against its stamped rating, is a standard bench test that directly verifies the thermostat's calibration. A dashboard gauge reading, by contrast, is influenced by many other variables in the cooling system such as sender accuracy, airflow, and ambient conditions, so it cannot by itself confirm the thermostat's exact opening temperature.

Answer: A
When a compressor fails internally, metal debris and contamination circulate through the refrigerant system and commonly lodge in or plug the fixed orifice tube and settle in the accumulator; if that debris is not flushed and the orifice tube and accumulator are not replaced, the contamination will damage the replacement compressor again in short order, exactly matching a repeat failure. A condenser leak, blend door calibration, or ambient sensor reading are unrelated to compressor debris contamination and would not explain a second compressor failure so soon after replacement.

Answer: A
When both high-side and low-side pressures read below specification together, and there is no localized restriction or frost pattern anywhere in the system, the most common explanation is simply an insufficient total charge of refrigerant, typically from a small leak that has allowed the charge to drop over time. A restricted condenser would raise the high side while lowering the low side rather than lowering both together, and a stuck expansion valve, whether closed or open, would produce a localized pressure imbalance and frost pattern rather than both pressures reading uniformly low.

Answer: A
Moisture that has entered the refrigerant system, often because a receiver-drier or accumulator's desiccant has become saturated and can no longer absorb it, will freeze at the metering device as pressure and temperature drop there, progressively blocking refrigerant flow and causing the low side pressure to fall toward a vacuum; once the system sits off and the ice melts, the blockage clears and cooling returns temporarily. A condenser leak would show as a steady loss of charge rather than a cycling pattern, and a relay or sensor fault would not create this freeze-and-thaw pattern at the metering device.

Answer: D
The clutch cycling switch is meant to cycle the compressor off once the evaporator reaches a low enough temperature, preventing the core from freezing over; a switch stuck closed keeps the compressor running continuously past that point, allowing moisture on the evaporator to freeze into a heavy layer of ice that eventually blocks airflow almost completely. An undercharged system or restricted condenser would reduce cooling capacity rather than cause continuous unregulated compressor operation, and a recirculation door issue affects the source of intake air, not evaporator icing.

Answer: A
Air that becomes trapped in the refrigerant system, typically introduced during a service procedure that did not fully evacuate the system beforehand, does not condense in the condenser the way refrigerant does and instead occupies space and drives high-side pressure abnormally high relative to what the refrigerant type and ambient temperature alone would predict, while the low side and overall cooling are affected only mildly. An evaporator leak would lower charge and reduce both cooling and eventually pressure rather than spike the high side, and a clutch bearing or low-pressure switch fault would not create this specific pressure-versus-temperature mismatch.

Answer: C
R-134a and R-1234yf are different refrigerants that must never be mixed, and cross-contamination between them can damage a vehicle's system and create a safety hazard, which is why recovery, recycling, and recharging equipment for each refrigerant type is built to be dedicated and non-interchangeable, using different fitting sizes specifically to prevent accidental mixing. Simply wiping down hoses does not remove residual refrigerant and oil trapped inside internal passages and would not prevent contamination between the two refrigerant types.

Answer: D
Automatic climate control systems use the ambient air temperature reading as one of the inputs to calculate how much heating or cooling is needed and how to position the blend door; if that sensor reports a temperature far higher than actual, the module concludes less heating is needed than is really the case, producing exactly the pattern of blowing warmer than requested specifically in cold conditions where the sensor error is largest. A blend door actuator, recirculation door, or cabin filter fault would produce a consistent problem regardless of outside temperature rather than one tied specifically to cold mornings.

Answer: C
The evaporator temperature sensor's signal is used by the control module to decide when to cycle the compressor off to prevent evaporator icing and back on to maintain cooling; an erratic or jumping sensor signal can falsely indicate the evaporator has reached a cutoff temperature, causing the module to cycle the compressor rapidly even though the actual evaporator condition and refrigerant charge are normal. A restricted condenser, stuck expansion valve, or undercharge would each show up as abnormal pressures rather than as an erratic sensor signal with otherwise correct charge and no ice.

Answer: D
Refrigerant pressure at rest is closely tied to ambient temperature, so on a sufficiently cold morning system pressure can naturally sit low enough to be below the low-pressure cutout switch's threshold, which is designed to prevent compressor operation under conditions where there may not be enough refrigerant pressure to ensure adequate lubricant circulation; this is a normal protective function rather than a fault, and operation returning once temperatures rise later confirms it. A coil, condenser, or icing fault would not correlate so precisely with ambient temperature and would not clear up simply because the day warmed up.

Answer: D
Many blend door actuators must complete a calibration or relearn procedure after installation so the control module can identify the actuator's full range of travel and correlate specific positions with specific temperature outputs; skipping this step after a replacement commonly produces exactly the described symptom of inconsistent temperatures and a door that stops in the wrong place. A refrigerant recharge, sensor replacement, or cabin filter change would not correct a calibration mismatch introduced by installing a new actuator.

Answer: D
Many door actuators monitor their own current draw or travel during a self-test and report a stall fault when the motor cannot complete its expected range of motion, which is exactly what happens when a mechanical obstruction such as a broken bracket physically prevents the door from moving; finding that same binding when moving the linkage by hand confirms the mechanical cause. An oversized motor, refrigerant charge, or a calibrated blend door with a missing sensor would not produce a stall fault tied to mechanical binding found in the case.

Answer: B
Many HVAC control modules support a scan tool bi-directional test that commands each door actuator through its range while the technician listens and watches for correct response, allowing confirmation of whether the actuator and door move properly without disassembling the case at all. Disconnecting the battery only shows a default fail-safe position rather than diagnosing function, replacing a part without confirming the fault first is not a diagnostic step, and applying direct battery voltage bypasses the module's normal control logic and risks damaging the actuator or exceeding its designed travel.

Answer: D
Since the driver's side responds correctly and the passenger-side problem is consistent regardless of sunlight conditions, the fault is isolated to a zone-specific component rather than a shared input like the ambient sensor, which affects both zones, or the sunload sensor, whose effect would vary with sunlight; the most likely cause is the blend door actuator or door mechanism dedicated to the passenger-side zone failing to respond to commands. A clogged cabin filter would reduce airflow to both sides fairly evenly rather than affect temperature control on just one zone.

Answer: D
In a pulse-width-modulated blower system, the control module varies motor speed by rapidly switching voltage on and off at different duty cycles, so confirming correct duty cycle output on a scope rules out the control module and points the remaining fault to the motor itself; a motor that is mechanically binding or drawing excess current will not respond smoothly to those correctly varying commands even though the electrical signal reaching it is proper. A refrigerant leak, recirculation door, or sunload sensor issue have no relationship to blower motor speed response under PWM control.

Answer: B
Since the actuators pass their bi-directional test and the door itself moves smoothly, the mechanical side of the system is confirmed to be working, which points the fault to the position feedback signal that tells the control module where the door actually is; an erratic feedback signal causes the module to command the wrong compensating position because it believes the door is somewhere other than where it truly is, producing inconsistent cabin temperatures despite correct mechanical operation. A clutch relay, restricted condenser, or saturated drier are refrigeration-side components unrelated to a door position feedback signal.

Answer: A
A variable displacement compressor changes its output based on a control valve that responds to a signal from the control module; if the module is confirmed to be sending a correct maximum-displacement command but the system's actual cooling output does not follow that command, the fault lies with the control valve itself failing to properly adjust compressor displacement in response. A cabin air filter, in-vehicle sensor, or recirculation door issue would affect airflow or temperature calculation rather than the compressor's actual refrigerant output relative to a confirmed command.

Answer: A
Listening for actuator motor operation during a temperature change is a valid, quick preliminary check that can reveal whether the actuator is attempting to move at all, while a scan tool bi-directional test provides a more complete and definitive confirmation by commanding the actuator through its entire range and allowing direct observation of door movement and resulting airflow; both are legitimate diagnostic steps, with the scan tool test simply offering more thorough confirmation than the listening check alone.

Answer: A
Modules on a shared communication network exchange data with each other over that network, so a fault affecting the communication bus itself or a connector feeding it can disrupt several unrelated systems simultaneously, exactly as described with both the climate display and headlight automation acting up together; because the disruption spans systems that otherwise have nothing in common except sharing that network, a bus or connector fault is the most likely explanation. A single sensor, a heater core leak, or a cabin filter clog would each affect only its own specific system and would not explain simultaneous problems in unrelated features.

Answer: D
A restriction located just before the expansion valve, such as a clogged inlet screen or a partially blocked line, starves the valve of refrigerant, which drops both high-side and low-side pressure below normal, and the sudden pressure drop right at that restriction point causes moisture in the air to freeze on the line, producing the frost exactly at the valve inlet. An overcharged system would raise pressures rather than lower them, a failed clutch coil would prevent the compressor from running at all rather than produce a partial-pressure symptom, and a stuck-open low-pressure switch is an electrical fault that does not create a physical frost pattern.

Answer: C
Many blower circuits route low and medium speeds through a resistor assembly, while the highest speed is often supplied directly through a relay that bypasses the resistor. An open resistor interrupts every speed that depends on it while leaving the direct high-speed path intact, exactly matching this symptom. A seized motor or a clogged filter would affect airflow at every speed including high, and a miscalibrated control head would not selectively kill only the lower settings.

Answer: B
Engine coolant contains ethylene glycol, which has a sweet odor; a leaking heater core sprays a fine coolant mist directly into the airflow entering the cabin, and that mist condenses on the cool glass as an oily film even though the loss is too small to affect overall engine temperature. A clogged filter only reduces airflow without producing odor or film, a condenser problem affects refrigerant rather than coolant, and a stuck-open thermostat causes slow warm-up rather than a coolant smell.

Answer: A
A radiator cap that will not hold its rated pressure allows coolant to escape into the overflow hose at a lower-than-normal pressure, which matches frequent overflow loss without any overheating, since the system otherwise still cools adequately. A worn water pump bearing produces a leak at the weep hole rather than at the cap, a heater core leak shows up inside the cabin or under the dash, and a fan clutch issue would affect cooling performance, not cap sealing.

Answer: C
A viscous fan clutch normally allows the fan to spin freely at low speed when the engine is cold and only locks up to drive the fan at higher speed once airflow through the radiator needs to increase; a clutch that is stuck locked up drives the fan at full speed constantly, even from a cold start, and the resulting excess airflow through the radiator can pull engine temperature below normal in mild conditions. An electric fan relay does not apply to a belt-driven fan, a stuck-closed thermostat would cause overheating rather than over-cooling, and a collapsed hose restricts flow rather than driving the fan.

Answer: C
A motor that sounds like it is spinning at full speed but produces weak airflow at every setting points to a restriction downstream of the motor rather than an electrical or control problem, and a clogged cabin air filter is the most common and easiest cause of exactly this kind of uniform airflow loss across all speeds and modes. A blend door, control valve, or mode door fault would typically change temperature or where the air exits, not uniformly choke down volume at every setting.

Answer: A
Freeze protection in an engine cooling system is governed primarily by the ratio of antifreeze concentrate to water, and a mixture with too little concentrate and too much water will test at a higher, less protective, freeze point than the manufacturer's specification, regardless of the mechanical condition of the pump, thermostat, or cap, none of which affect the chemical freeze point of the fluid itself.

Answer: A
A wobbling pulley with the belt removed indicates play in the water pump's internal bearing, and that wobble misaligns the pulley enough to cause the belt to squeal as it runs, with the pitch changing alongside engine and pump speed. A collapsed hose or stuck thermostat would affect coolant flow and temperature but would not cause a squeal or pulley wobble, and refrigerant charge level has no relationship to the belt-driven cooling system at all.

Answer: A
Recirculation mode reduces the load on the air conditioning system by conditioning already-cooled cabin air instead of hot outside air; a recirculation door stuck in the outside-air position forces the system to continuously process hot humid outside air, which can produce weak-feeling cooling even when the refrigeration side is working correctly and pressures test normal. A restricted condenser, failing clutch, or overcharge would each show up as abnormal refrigerant pressures, which is not the case here.

Answer: D
Pressurizing the cooling system with a hand pump tester reproduces the operating pressure the system sees when running, which reveals slow or small external leaks at hoses, gaskets, or fittings that would otherwise not show up as visible puddles between drives. Simply replacing the cap, flushing the system, or swapping the thermostat are guesses that do not actually locate where the coolant is escaping and could leave the real leak unaddressed.

Answer: D
Since refrigerant charge and the pressure switches all test normal, the refrigeration side of the system is ruled out, and the absence of battery voltage at the clutch coil connector when the system commands the compressor on points directly to a fault in the relay or the wiring that supplies that voltage to the coil. A condenser restriction, evaporator icing, or expansion valve fault would each affect refrigerant pressures rather than prevent voltage from reaching the coil in the first place.

Answer: C
Both pressures reading well above specification together, following a recent recharge, along with weak cooling despite the compressor cycling normally, is the classic pattern of too much refrigerant in the system; excess refrigerant floods the condenser and evaporator and reduces the system's ability to properly change state and absorb heat. A restricted orifice tube would push the high side up while pulling the low side down rather than raising both, and a clutch coil fault or evaporator leak would not raise pressures at all.

Answer: B
The condenser needs airflow to reject heat from the refrigerant, and fins packed with debris reduce that airflow, which is most noticeable at idle and low speed where there is little ram air to compensate; the resulting poor heat rejection raises high side pressure while the low side stays closer to normal because the compressor is still pumping refrigerant through the circuit adequately. An undercharged system or stuck expansion valve would lower pressures or create a different pressure split rather than elevate only the high side with a speed-dependent pattern, and a low-pressure switch fault would prevent compressor operation rather than change pressure readings while it runs.

Answer: C
A clanking noise tied specifically to clutch engagement, together with visible metal shavings at the compressor's suction port, points directly to internal mechanical failure inside the compressor itself, such as damaged pistons, vanes, or bearings shedding metal as it runs. A restricted expansion valve or saturated drier would affect pressures and cooling performance rather than produce metal debris and a clanking noise from the compressor, and a weak clutch coil would cause slipping or failure to engage rather than an internal noise.

Answer: D
Refrigerant oil travels through the system suspended in and carried along with the refrigerant itself, so when the charge runs chronically low, less oil is circulated and returned to the compressor over time, starving it of lubrication and leading to premature wear or failure. Low charge does not directly corrode bearings, and while clutch slippage or refrigerant velocity can cause other problems, they are not the established mechanism connecting a slow leak to compressor lubrication failure.

Answer: C
A sunload sensor detects the intensity and direction of sunlight entering the cabin so the control module can add extra cooling on the side receiving direct sun to keep both zones feeling equal; a failed sensor on the affected side means the module never compensates for sun load there, and the mismatch only appears when the sun is actually out and disappears at night or under clouds when there is no sun load to compensate for. A stuck blend door, resistor fault, or heater core leak would each produce a temperature difference regardless of sunlight conditions, not one tied specifically to sun exposure.

Answer: B
The in-vehicle temperature sensor relies on a small aspirator motor to continuously draw a fresh sample of cabin air past it so the reading reflects current conditions; if the aspirator or its tube is blocked, the sensor instead reads whatever air is trapped near it, which lags well behind the actual cabin temperature and causes the control module to respond slowly to temperature changes since it is working from stale data. This blockage has no direct effect on compressor clutch engagement, permanent blend door position, or refrigerant charge, none of which are connected to the aspirator or sensor tube.

Answer: C
A high-pressure cutoff switch is a protective device that opens the compressor circuit when high-side pressure climbs to an unsafe level, so a switch that is repeatedly tripping is doing its job correctly in response to a real high-side pressure spike, and the underlying cause to investigate is whatever is driving that pressure up, most commonly restricted condenser airflow or a cooling fan that is not running to help reject heat. The evaporator sensor, blend door, and ambient sensor are all unrelated to what generates high-side refrigerant pressure.

Answer: D
Modern HVAC and engine control modules often withhold a compressor-on command based on other inputs shared over the vehicle's communication network, such as high coolant temperature or wide-open throttle, as a way to protect engine performance or prevent overheating, even when the pressure switches themselves show no fault; since the coil and relay path test fine electrically, the missing command itself is the next thing to investigate, tracing back through the inputs and communication feeding that decision. A condenser leak, blend door wiring, or cabin filter clog have no bearing on whether the module decides to send a compressor-on command in the first place.

Answer: C
An audible click confirms the relay's coil is energizing and the armature is moving as expected, but if no voltage appears at the output terminal despite that click, the contacts inside the relay that are supposed to pass current through to the clutch coil have most likely worn or burned to the point where they no longer make a solid electrical connection even though they mechanically move. An open clutch coil winding, a blown fuse, or a failed pressure switch would each prevent voltage from ever reaching or passing through the relay in the first place, rather than allowing it to click without passing current.

Answer: C
A symptom that correlates specifically with door movement strongly suggests a wiring or connector issue located near the door hinge, sill, or kick panel area, where a harness can flex every time the door opens and closes and gradually wear through insulation or loosen a connector, creating an intermittent short or open circuit tied to that motion. A resistor, evaporator sensor, or heater control valve fault would not have any reason to correlate with door movement specifically.

Answer: C
On orifice-tube systems, the clutch cycling switch monitors low-side pressure or temperature as an indicator of evaporator conditions and is typically mounted on or near the accumulator on the low side of the system, since that pressure closely tracks evaporator temperature and provides the signal needed to cycle the compressor to prevent icing. It is not located on the high-side line, threaded into the condenser, or built into the dashboard control head, none of which provide a suitable signal for this function.

Answer: B
Vacuum-actuated systems rely on engine manifold vacuum to hold doors in their commanded position, and available vacuum naturally drops when the engine is under load, such as during acceleration; a hose or actuator with a leak that is small enough to be masked by strong vacuum at idle can become significant once vacuum drops under load, causing the doors to drift toward their vacuum-off fail-safe position, which is commonly defrost. A blower resistor, refrigerant overcharge, or ambient sensor fault has no connection to vacuum-operated door behavior tied to engine load.

Answer: A
A high-pressure cutoff switch is a protective device that opens the compressor circuit when high-side pressure climbs to a level that could damage system components, while a low-pressure cutout switch opens the circuit when low-side pressure drops too low, which is primarily a concern because refrigerant oil circulates along with the refrigerant and insufficient pressure can mean insufficient lubricant return to the compressor; both descriptions accurately describe the distinct protective functions of these two switches.

Answer: B
An electronic pressure transducer is expected to produce a voltage output that varies continuously with actual system pressure so the control module can make accurate compressor cycling decisions; an output that stays fixed at one value regardless of real pressure changes indicates the transducer itself or its wiring has failed rather than any change in the refrigeration side of the system, since a genuine drier, condenser, or expansion valve problem would change actual system pressure and therefore still produce a changing transducer signal to match.

Answer: D
An electrically driven, high-voltage compressor is wired directly into the vehicle's high-voltage system and can retain dangerous voltage even after the vehicle is shut off, so before any service that involves opening the compressor or its fittings, the manufacturer's specific high-voltage disable and lockout procedure must be followed and insulated, high-voltage-rated tools must be used to prevent electrical shock. Recovering refrigerant alone ignores the electrical hazard, disconnecting only the low-voltage battery does not de-energize the separate high-voltage system, and grounding the refrigerant lines does nothing to address the high-voltage hazard inside the compressor itself.