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EPA 609 practice questions

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Question 1Proper use of MVAC servicing equipment

A technician is preparing to recharge an MVAC system and must remove moisture from the refrigerant before charging. Which piece of equipment is designed for this purpose?

  1. A vacuum pump
  2. A refrigerant identifier
  3. A recovery/recycling machine with a filter-drier Correct answer.
  4. A manifold gauge set

Explanation

A recovery/recycling machine passes refrigerant through a filter-drier and separator to remove moisture and particulates as part of the recycling process. A vacuum pump removes air and moisture from the system itself, not from refrigerant being charged.

Question 2Proper use of MVAC servicing equipment

Which refrigerant is permitted for use in motor vehicle air conditioning systems under EPA 609 rules, and requires a certified technician to handle it?

  1. R-410A
  2. R-717
  3. R-22
  4. HFC-134a Correct answer.

Explanation

HFC-134a is a common MVAC refrigerant regulated under Section 609, and technicians must be certified to service systems containing it. R-22, R-410A, and ammonia are stationary or industrial refrigerants outside the MVAC scope.

Question 3Proper use of MVAC servicing equipment

Before opening an MVAC system for service, what must a technician do to the refrigerant in the system?

  1. Seal it in the system and proceed
  2. Dilute it with air
  3. Recover it with approved equipment Correct answer.
  4. Vent it to the atmosphere slowly

Explanation

Section 609 prohibits venting refrigerant to the atmosphere. Refrigerant must be recovered using certified recovery or recovery/recycling equipment before any system component is opened.

Question 4Proper use of MVAC servicing equipment

A technician uses a manifold gauge set to service an MVAC system. What is the primary function of this tool?

  1. To recover refrigerant from the system
  2. To measure and display system high- and low-side pressures Correct answer.
  3. To weigh the refrigerant charge
  4. To detect refrigerant leaks electronically

Explanation

A manifold gauge set connects to the high and low service ports and displays system pressures so the technician can diagnose performance. Recovery, leak detection, and charging by weight use separate dedicated equipment.

Question 5Proper use of MVAC servicing equipment

During recovery, a technician notices the recovery machine's filter-drier is saturated. What is the correct action?

  1. Increase the recovery machine's operating pressure
  2. Continue recovery and replace the drier at the next service interval
  3. Bypass the drier to speed recovery
  4. Replace the filter-drier before continuing Correct answer.

Explanation

A saturated filter-drier cannot remove moisture and can restrict flow, so it must be replaced before recovery continues. Continuing with a spent drier risks contaminating recovered refrigerant and damaging the machine.

Question 6Proper use of MVAC servicing equipment

Which practice correctly prevents cross-contamination when servicing systems that use different refrigerants?

  1. Mixing recovered refrigerants in one tank
  2. Flushing the system with compressed air
  3. Using the same recovery machine for all refrigerants without cleaning
  4. Dedicating recovery equipment or thoroughly evacuating it between refrigerants Correct answer.

Explanation

Mixing refrigerants makes them unreclaimable and can damage equipment. Using dedicated recovery equipment or thoroughly evacuating shared equipment between different refrigerants prevents cross-contamination.

Question 7Proper use of MVAC servicing equipment

A technician is evacuating an MVAC system with a vacuum pump. Why is a deep vacuum held for a period of time?

  1. To raise the system pressure for leak testing
  2. To charge the system with refrigerant
  3. To boil off moisture and confirm the system holds vacuum Correct answer.
  4. To test the compressor clutch

Explanation

Pulling and holding a deep vacuum lowers the boiling point of water so residual moisture vaporizes and is removed, and holding the vacuum confirms there are no leaks. It is not a charging or pressure-raising step.

Question 8Proper use of MVAC servicing equipment

What is the purpose of a refrigerant identifier when servicing an unknown vehicle?

  1. To recharge the system by weight
  2. To measure system oil level
  3. To recover refrigerant automatically
  4. To verify the refrigerant type and detect contamination before recovery Correct answer.

Explanation

A refrigerant identifier analyzes the gas to confirm which refrigerant is present and to detect contamination or flammable blends before recovery. This protects the technician and prevents mixing incompatible refrigerants.

Question 9Proper use of MVAC servicing equipment

A recovery cylinder is being filled during service. What rule governs how full it may be filled?

  1. Fill to no more than 80 percent of the cylinder's capacity Correct answer.
  2. Fill to 100 percent of gross weight
  3. Fill until the pressure relief valve vents
  4. Fill to the cylinder's tare weight

Explanation

Recovery cylinders must not be filled beyond 80 percent of capacity to allow for liquid expansion as temperature rises. Overfilling can cause hydrostatic pressure buildup and cylinder rupture.

Question 10Proper use of MVAC servicing equipment

Which action is required before a recovery/recycling machine is used on a system for the first time after servicing?

  1. Verify the machine is certified and check the filter-drier and oil separator Correct answer.
  2. Open the high-side valve fully
  3. Purge the machine with nitrogen
  4. Disconnect the low-side hose

Explanation

Certified recovery/recycling equipment must be maintained so its filter-drier and oil separator function properly. Verifying certification and component condition ensures recovered refrigerant meets reuse standards.

Question 11Proper use of MVAC servicing equipment

A technician must determine whether recovered refrigerant can be returned to the same vehicle. Which condition allows reuse in that vehicle?

  1. The refrigerant was recycled to the required purity and the system is the same one Correct answer.
  2. The refrigerant was vented and recaptured
  3. The refrigerant was recovered from any vehicle and filtered once
  4. The refrigerant was mixed with another type and then dried

Explanation

Refrigerant recycled to the required purity may be charged back into the same vehicle from which it was recovered. Refrigerant of unknown or mixed composition cannot be reused and must be sent for reclamation.

Question 12Proper use of MVAC servicing equipment

When charging an MVAC system, why is the refrigerant typically added as a liquid to the high side with the system off?

  1. To speed up the vacuum process
  2. To test the expansion valve
  3. To avoid liquid slugging the compressor Correct answer.
  4. To raise the low-side pressure

Explanation

Adding liquid refrigerant to the high side with the compressor off prevents liquid from entering and damaging the compressor. Charging as vapor through the low side is used when the system is running.

Question 13Proper use of MVAC servicing equipment

A technician's recovery machine is rated for a given refrigerant, but the system contains a flammable refrigerant blend. What is the correct action?

  1. Recover it with the standard machine
  2. Vent it because it is flammable
  3. Mix it with R-134a to dilute it
  4. Use equipment rated for flammable refrigerants and follow specific procedures Correct answer.

Explanation

Flammable refrigerants require recovery equipment rated for flammable service and specific safety procedures to prevent ignition. Standard equipment and venting are unsafe and prohibited.

Question 14Proper use of MVAC servicing equipment

What is the correct way to handle a recovery cylinder that has reached its fill limit during a job?

  1. Store the full cylinder in direct sunlight
  2. Continue filling until the job is done
  3. Switch to an empty recovery cylinder and label the full one Correct answer.
  4. Vent the excess to make room

Explanation

A full recovery cylinder must be replaced with an empty one, and cylinders should be labeled with their contents. Continuing to fill or venting excess violates safe handling rules.

Question 15Proper use of MVAC servicing equipment

A technician is using a recovery machine and notices the recovery rate has slowed dramatically with the system nearly empty. What is a likely cause?

  1. The manifold gauges are misconnected
  2. The recovery machine's filter is clogged or the system is very cold Correct answer.
  3. The system is overcharged
  4. The compressor clutch is engaged

Explanation

As recovery nears completion, low system pressure and cold temperatures slow evaporation, and a clogged filter restricts flow. Checking the filter and allowing the system to warm can restore recovery rate.

Question 16Proper use of MVAC servicing equipment

Which statement correctly describes the relationship between recovery, recycling, and reclamation?

  1. Recovery removes refrigerant; recycling cleans it on site; reclamation reprocesses it to specification off site Correct answer.
  2. Recycling sends refrigerant to a reclaimer; recovery cleans it
  3. All three terms mean the same process
  4. Recovery cleans refrigerant; recycling removes it; reclamation vents it

Explanation

Recovery is the removal of refrigerant from a system, recycling is on-site cleaning through a recovery/recycling machine, and reclamation is off-site reprocessing to a purity specification. Keeping these terms distinct matters for compliance and reuse decisions.

Question 17Proper use of MVAC servicing equipment

A technician recovers refrigerant from a system, then must decide whether to reuse it or send it for reclamation. Which factor most directly determines this decision?

  1. The color of the recovery cylinder
  2. Whether the refrigerant meets purity standards for the intended use Correct answer.
  3. The length of the service hoses
  4. The ambient temperature during recovery

Explanation

Reuse depends on whether the recovered refrigerant meets the purity standard required for the intended use, such as returning it to the same vehicle. Refrigerant that fails purity standards must be reclaimed.

Question 18Proper use of MVAC servicing equipment

During recovery, a technician observes that the recovery machine's oil separator is collecting an unusual amount of oil. What does this indicate and what should be done?

  1. The filter-drier is new; no action is needed
  2. The refrigerant is contaminated; vent it
  3. Excess oil is being carried out with refrigerant; measure and replace system oil as needed Correct answer.
  4. The system is low on oil; add oil to the system

Explanation

Recovery can carry system oil into the machine's oil separator, so the amount removed must be measured and replaced in the system to maintain lubrication. Excess oil removal without replacement can damage the compressor.

Question 19Proper use of MVAC servicing equipment

A technician is setting up a recovery/recycling machine. Which connection practice is correct?

  1. Leave the hoses disconnected until the machine runs
  2. Connect the high-side hose to the low-side port to speed recovery
  3. Connect only the low-side hose for liquid recovery
  4. Connect hoses to the service ports and purge air from the hoses before recovery Correct answer.

Explanation

Hoses should be connected to the correct service ports and air purged from the lines before recovery to prevent introducing non-condensables. Correct port connection ensures liquid and vapor are recovered properly.

Question 20Proper use of MVAC servicing equipment

What is the primary safety reason for wearing safety glasses and gloves when working with refrigerant and recovery equipment?

  1. To protect against frostbite and eye injury from liquid refrigerant Correct answer.
  2. To keep hands clean
  3. To prevent static electricity
  4. To improve grip on tools

Explanation

Liquid refrigerant can cause frostbite and severe eye injury on contact, so safety glasses and gloves are required. Personal protective equipment protects against these physical hazards.

Question 21Proper use of MVAC servicing equipment

Which of the following is required for a technician to legally purchase refrigerant under Section 609?

  1. A business license only
  2. A driver's license
  3. A manufacturer's warranty card
  4. Section 609 certification Correct answer.

Explanation

Section 609 certification is required to purchase refrigerant for MVAC servicing. The certification demonstrates knowledge of safe handling and environmental rules.

Question 22Proper use of MVAC servicing equipment

A technician must dispose of a recovery cylinder that is no longer usable. What is the proper handling?

  1. Vent remaining refrigerant and recycle the steel
  2. Return it to a refrigerant supplier or reclaimer for proper disposal Correct answer.
  3. Store it outdoors indefinitely
  4. Place it in regular trash

Explanation

Recovery cylinders and any remaining refrigerant must be handled through a supplier or reclaimer that can properly recover contents and dispose of the cylinder. Regular trash disposal is improper.

Question 23Proper use of MVAC servicing equipment

What does a leak detector's sensitivity setting affect during MVAC leak testing?

  1. The system's operating pressure
  2. The refrigerant charge level
  3. The compressor speed
  4. The ability to detect small leaks Correct answer.

Explanation

Leak detector sensitivity determines how small a leak the instrument can detect. Proper calibration and setting help find leaks without false readings.

Question 24Proper use of MVAC servicing equipment

A technician is about to recover refrigerant from a system that has not been identified. What is the safest first step?

  1. Identify the refrigerant with an identifier and check for contamination Correct answer.
  2. Begin recovery immediately
  3. Vent a small sample to smell it
  4. Add R-134a to standardize the system

Explanation

Identifying the refrigerant and checking for contamination prevents mixing incompatible refrigerants and protects equipment and personnel. Recovery should not begin until the refrigerant type is known.

Question 25Proper use of MVAC servicing equipment

Which statement best explains why recovered refrigerant must be stored in DOT-approved recovery cylinders?

  1. They allow venting when full
  2. They are cheaper than other containers
  3. They eliminate the need for labeling
  4. They are designed and rated to safely contain pressurized refrigerant Correct answer.

Explanation

DOT-approved recovery cylinders are rated for the pressure of refrigerants and are designed for safe transport and storage. Using unapproved containers risks rupture and violates handling requirements.

Question 26Proper use of MVAC servicing equipment

A technician is about to connect a recovery/recycling machine to an MVAC system and wants to purge air from the service hoses before recovery begins. Which procedure accomplishes this correctly?

  1. Loosen both hose fittings at the system service ports while the machine is running in recovery mode
  2. Crack the hose fittings slightly at the machine with the system valves closed and bleed a small amount of refrigerant, then tighten Correct answer.
  3. Blow shop air through the hoses with a nozzle before attaching them to the system
  4. Leave the hoses attached overnight so any trapped air migrates into the recovery cylinder

Explanation

Trapped air in service hoses is non-condensable and will raise discharge pressures and contaminate the recovered charge. The accepted practice is to purge each hose by briefly cracking the connection at the machine while system valves are closed, allowing refrigerant to sweep the air out. This must be done before recovery starts so the contaminant never enters the recovery cylinder.

Question 27Proper use of MVAC servicing equipment

A recovery/recycling machine is equipped with a filter-drier in its recycling circuit. What is the function of that filter-drier during the recycling phase?

  1. It removes moisture and acid products from the refrigerant as it circulates Correct answer.
  2. It provides the pressure relief protection required for the recovery cylinder
  3. It separates refrigerant vapor from liquid before the compressor inlet
  4. It measures the weight of refrigerant transferred into the storage cylinder

Explanation

The filter-drier in a recovery/recycling machine is a desiccant core that traps moisture and acid contaminants while refrigerant passes through the recycling loop. It does not meter refrigerant or provide pressure relief. Its condition directly affects whether recycled refrigerant meets the purity needed for reuse in the same vehicle.

Question 28Proper use of MVAC servicing equipment

A technician is weighing refrigerant into an MVAC system using a recovery/recycling machine with a built-in electronic scale. Which practice gives an accurate charge?

  1. Zero the scale after the first kilogram has been transferred
  2. Tare the scale with the cylinder and hoses in place before charging begins Correct answer.
  3. Compensate by adding ten percent to the nameplate charge to cover hose losses
  4. Read the charge from the machine's high-side gauge instead of the scale

Explanation

An electronic charge scale must be tared with the source cylinder, hoses, and any adapters in place so the displayed value reflects only refrigerant transferred. Zeroing after transfer begins or estimating from gauges introduces error. Hoses hold liquid refrigerant that is part of the system charge, so no arbitrary percentage should be added.

Question 29Proper use of MVAC servicing equipment

When a recovery/recycling machine finishes recovering a system, the technician should verify completion by confirming which condition?

  1. The system has held the specified vacuum level for the required time with the machine isolated Correct answer.
  2. The machine's oil separator has stopped collecting oil
  3. The recovery cylinder feels cool to the touch
  4. The high-side gauge reads zero while the compressor is still running

Explanation

Recovery is complete when the system reaches and holds the vacuum level specified for the equipment and refrigerant, with the system isolated from the machine. A zero pressure reading on a running system does not prove evacuation, and temperature or oil clues are indirect. Holding vacuum demonstrates that refrigerant has been removed and that no leak is admitting air.

Question 30Proper use of MVAC servicing equipment

A technician is preparing to leak-test an MVAC system with an electronic refrigerant leak detector. Which step best improves the reliability of the test?

  1. Spray soap solution on the fittings first, then probe with the electronic detector
  2. Test immediately after charging while the system is at maximum pressure and the engine is at high idle
  3. Test in still air with the engine and blower off, probing slowly below and around each joint Correct answer.
  4. Run the blower on high to disperse refrigerant so the sensor can find the source

Explanation

Electronic detectors respond to refrigerant concentration, so air movement from the engine fan or blower can dilute or scatter the trace and cause missed or false readings. Probing slowly near joints, especially below them where refrigerant is denser than air, improves detection. Soap residue can also affect some sensors.

Question 31Proper use of MVAC servicing equipment

A technician is using a manifold gauge set on an MVAC system. Which practice protects the equipment and the technician?

  1. Fully open both hand valves before attaching the hoses to the service ports
  2. Leave the hoses connected to the system whenever the gauges are stored
  3. Open valves slowly and keep hands clear of the gauge faces and hose connections Correct answer.
  4. Use the gauges to vent refrigerant to the atmosphere when pressures seem high

Explanation

Manifold gauges contain refrigerant under pressure, and sudden valve operation can cause hydraulic shock, hose whip, or frostbite. Opening valves gradually and keeping hands away from connections limits exposure. Gauges must not be used to deliberately vent refrigerant, and hoses should be disconnected and capped for storage.

Question 32Proper use of MVAC servicing equipment

A recovery/recycling machine's compressor begins short-cycling during recovery. Which cause should the technician investigate first?

  1. A system that has already been fully recovered
  2. A recovery cylinder that is too cold
  3. A filter-drier that is brand new
  4. A restricted or closed valve in the recovery path that is raising suction pressure Correct answer.

Explanation

Short-cycling usually indicates the machine's high-pressure or low-pressure control is tripping because of abnormal suction or discharge conditions. A closed valve or restriction in the recovery path raises pressure and is a common cause. Cylinder temperature and filter age are not typical triggers for cycling, and a fully recovered system would simply stop rather than cycle.

Question 33Proper use of MVAC servicing equipment

Which item must be verified on a recovery cylinder before it is used to store recovered refrigerant?

  1. That the cylinder has been evacuated and left open to atmosphere
  2. That the cylinder is DOT-approved for the refrigerant and its hydrostatic test date is current Correct answer.
  3. That the cylinder is fitted with a Schrader valve on the liquid line
  4. That the cylinder has been painted a light color to reflect sunlight

Explanation

Recovery cylinders must be DOT-approved for the specific refrigerant service and must have a current hydrostatic test date; using an out-of-date cylinder is a safety and legal violation. The cylinder must be evacuated before filling, never left open, and color or valve style alone does not establish suitability.

Question 34Proper use of MVAC servicing equipment

During recovery, a technician notices frost forming on the recovery cylinder and the recovery rate slowing. What is the appropriate response?

  1. Allow the cylinder to warm, or use a cylinder heater designed for the purpose, to maintain pressure Correct answer.
  2. Disconnect the cylinder and vent a small amount of refrigerant to warm it
  3. Add a second recovery cylinder in series with the first
  4. Increase the recovery machine's speed setting beyond its rated maximum

Explanation

As liquid refrigerant evaporates into the cylinder, the cylinder cools and internal pressure drops, which reduces the pressure differential that drives recovery. Warming the cylinder within safe limits restores the differential. Running equipment beyond rated limits or venting refrigerant is never acceptable.

Question 35Proper use of MVAC servicing equipment

A technician is deciding how to store a recovery/recycling machine between jobs. Which practice keeps the equipment ready and compliant?

  1. Store the machine with hoses attached to a cylinder to save time
  2. Cap or plug the hose ends and store the machine with its valves closed Correct answer.
  3. Leave the machine's compressor running briefly to clear the lines, then store it open
  4. Drain the machine's oil separator into a shop drain after each use

Explanation

Capping or plugging hoses and closing valves prevents moisture and air from entering the machine and prevents refrigerant from escaping. Oil removed from the separator is a regulated waste and must not go to a drain. Storing with hoses attached invites contamination and accidental release.

Question 36Proper use of MVAC servicing equipment

A technician is recovering refrigerant from a system and the recovery machine's inlet filter becomes clogged with debris. What is the correct action?

  1. Stop recovery, recover the refrigerant in the machine's lines, and replace or clean the filter as the manufacturer specifies Correct answer.
  2. Continue recovery and clean the filter after the cylinder is full
  3. Bypass the filter temporarily so recovery can finish
  4. Increase suction by opening the manifold's high-side valve to the low side

Explanation

A clogged inlet filter starves the compressor and can cause overheating or contamination of the recovered charge. The machine should be shut down, residual refrigerant recovered from its lines, and the filter serviced per the manufacturer. Bypassing the filter or continuing operation risks damage and contaminated refrigerant.

Question 37Proper use of MVAC servicing equipment

Before using a recovery/recycling machine on a system, a technician should confirm the machine is rated for which condition?

  1. The vehicle's model year and VIN
  2. The size of the vehicle's condenser
  3. The specific refrigerant in the system and the system's oil type Correct answer.
  4. The ambient temperature at the shop

Explanation

Recovery equipment must be rated for the refrigerant being handled, and the oil type matters because lubricant carried over can affect the machine and the recovered charge. Model year, VIN, ambient temperature, and condenser size do not determine equipment compatibility, though ambient conditions affect recovery speed.

Question 38Proper use of MVAC servicing equipment

A technician has recovered refrigerant into a cylinder and must label it. Which information is essential on the cylinder label?

  1. The vehicle's license plate number
  2. The technician's certification number only
  3. The ambient temperature at the time of recovery
  4. The refrigerant identity and the date the cylinder was filled Correct answer.

Explanation

Recovery cylinders must be identified by refrigerant type and fill date so that contents are not mixed and so that the material can be tracked for recycling or reclamation. Vehicle and ambient data are not required identifiers, and a certification number alone does not identify the contents.

Question 39Proper use of MVAC servicing equipment

A technician is deciding whether recovered refrigerant can be recycled on site or must be sent for reclamation. Which factor most directly determines this?

  1. Whether the cylinder is new or previously used
  2. Whether the recovered refrigerant meets the purity standard for the intended reuse Correct answer.
  3. Whether the recovery machine has a built-in scale
  4. Whether the system used PAG or mineral oil

Explanation

On-site recycling can only return refrigerant to service if the processed refrigerant meets the applicable purity specification. If contamination or mixing prevents that, the refrigerant must go to a reclamation facility. Scale presence, oil type, and cylinder age do not by themselves determine the disposition.

Question 40Proper use of MVAC servicing equipment

When transferring recovered refrigerant from a recovery machine into a storage cylinder, which practice is correct?

  1. Use a cylinder that previously held a different refrigerant without evacuation
  2. Confirm the cylinder is rated for the refrigerant, is not overfilled, and is connected liquid-tight before transfer Correct answer.
  3. Fill the cylinder until liquid is visible at the valve
  4. Transfer with the cylinder valve fully open to atmosphere

Explanation

Transfer requires a compatible, correctly rated cylinder that will not be overfilled, with tight connections to prevent release. Filling until liquid appears risks overfill and hydraulic damage, and reusing an unevacuated cylinder of another refrigerant contaminates the charge.

Question 41Proper use of MVAC servicing equipment

A technician is using a vacuum pump to evacuate an MVAC system after repair. Which practice protects the pump and the system?

  1. Leave the pump oil in service indefinitely because it does not absorb moisture
  2. Connect the pump directly to the high-side port only and leave the low side closed
  3. Run the pump without a vacuum gauge and rely on sound to judge completion
  4. Use a vacuum pump rated for the refrigerant and change its oil as needed to prevent moisture buildup Correct answer.

Explanation

Vacuum pump oil absorbs moisture and loses sealing ability, so it must be changed per the manufacturer to reach and hold a deep vacuum. The pump should be connected so both sides of the system are evacuated, and a gauge is required to verify the vacuum level.

Question 42Proper use of MVAC servicing equipment

A technician is checking a recovery/recycling machine before the day's first job. Which check belongs on the pre-use inspection?

  1. Confirm the machine's compressor has been running for an hour
  2. Verify the vehicle's refrigerant charge label matches the machine's serial number
  3. Confirm the cylinder is filled to its maximum before starting
  4. Verify hose condition, valve positions, scale zero, and that the storage cylinder has capacity Correct answer.

Explanation

A pre-use inspection should confirm hoses are sound, valves are in the correct starting position, the scale reads zero, and the receiving cylinder has room for the expected charge. Serial numbers and warm-up periods are not relevant checks, and starting with a full cylinder risks overfill.

Question 43Proper use of MVAC servicing equipment

A technician suspects a recovery/recycling machine is pulling air into the system during recovery. Which observation would support that suspicion?

  1. The system's low-side pressure falls as recovery proceeds
  2. The machine's scale counts upward during recovery
  3. The recovery cylinder pressure stays higher than expected and the machine cannot reach the required vacuum Correct answer.
  4. The recovery cylinder becomes cold during transfer

Explanation

Air is a non-condensable gas, so a leak into the recovery path shows up as elevated cylinder pressure that does not fall with temperature and as an inability to reach the specified vacuum. Cooling during transfer and falling system pressure are normal signs of recovery, and the scale counting up simply reflects refrigerant transferred.

Question 44Proper use of MVAC servicing equipment

Which practice is correct when a technician uses a recovery/recycling machine to service a system that has both high-side and low-side service ports?

  1. Recover from whichever port is closest to the compressor
  2. Recover from the high side only, because vapor recovery is unnecessary
  3. Recover from both ports as the equipment instructions direct so liquid and vapor are removed Correct answer.
  4. Recover from the low side only, because liquid will damage the machine

Explanation

Recovering from both sides, following the equipment manufacturer's procedure, removes liquid from the high side and vapor from the low side efficiently and completely. Using only one port leaves refrigerant behind or risks liquid slugging the compressor. Port location is not the deciding factor.

Question 45Proper use of MVAC servicing equipment

A technician is about to charge an MVAC system and must ensure the correct refrigerant is used. Which equipment-based step best prevents a wrong-refrigerant charge?

  1. Assume the refrigerant matches the vehicle's model year
  2. Rely on the color of the service-port caps
  3. Identify the refrigerant with an identifier and compare it to the system's specified refrigerant before charging Correct answer.
  4. Charge a small amount and check whether the system cools

Explanation

A refrigerant identifier confirms what is actually in the cylinder or system, and comparing that result to the vehicle specification prevents a wrong or contaminated charge. Port cap color and model year are unreliable indicators, and trial charging risks contaminating the system and the recovery equipment.

Question 46Proper use of MVAC servicing equipment

A technician is recovering refrigerant and the machine's oil separator must be drained. How should the recovered oil be handled?

  1. Collect it in a labeled container and manage it as regulated waste Correct answer.
  2. Pour it into the used-oil tank with engine oil without labeling
  3. Dispose of it in the shop's parts washer
  4. Return it to the vehicle's compressor

Explanation

Oil drained from a recovery machine contains dissolved refrigerant and must be collected in a closed, labeled container and managed as regulated waste. It should not be returned to the system, mixed unlabeled with other waste, or put into a parts washer, all of which can release refrigerant or create disposal problems.

Question 47Proper use of MVAC servicing equipment

Which statement correctly describes the role of a scale during recovery with a recovery/recycling machine?

  1. It shows how much refrigerant has been removed and helps prevent overfilling the storage cylinder Correct answer.
  2. It controls the machine's compressor speed automatically
  3. It replaces the need for a vacuum gauge during evacuation
  4. It measures the purity of the recovered refrigerant

Explanation

A scale tracks the mass of refrigerant transferred, which lets the technician know how much has been recovered and how much room remains in the cylinder. It does not assess purity, govern compressor speed, or substitute for vacuum measurement.

Question 48Proper use of MVAC servicing equipment

A technician must evacuate an MVAC system that has just been repaired and contains residual moisture. Which equipment practice improves moisture removal?

  1. Evacuate only until the gauge first shows vacuum, then stop
  2. Use a deep vacuum with a gauge and allow extra hold time, keeping the pump oil fresh Correct answer.
  3. Use the recovery machine's compressor to evacuate the system
  4. Pull a shallow vacuum quickly and charge immediately

Explanation

Moisture boils off only at sufficiently low absolute pressure, so a deep vacuum held for the specified time with a gauge and fresh pump oil is needed to remove it. A shallow or brief vacuum leaves water in the system, and a recovery machine is not designed to evacuate a system.

Question 49Proper use of MVAC servicing equipment

A technician is preparing to use a recovery/recycling machine that has just returned from another shop. Which step should be taken before connecting it to a customer's system?

  1. Connect it and begin recovery to test it on the customer's system
  2. Assume the machine is clean because it was used professionally
  3. Inspect and purge the hoses and confirm the machine's filter-drier and oil are serviceable Correct answer.
  4. Flush the machine with the customer's refrigerant after recovery begins

Explanation

Equipment from another shop may carry residual refrigerant, moisture, or debris, so hoses should be inspected and purged and the filter-drier and oil checked before use. Testing on a customer's system risks contamination, and flushing with the customer's refrigerant after recovery starts is too late to protect the charge.

Question 50Proper use of MVAC servicing equipment

When a recovery/recycling machine is used to recycle refrigerant for return to the same vehicle, which condition must be met?

  1. The refrigerant must be transferred through the low-side port only
  2. The refrigerant must be processed through the machine's recycling circuit and meet the applicable purity standard Correct answer.
  3. The machine must be operated at its maximum speed
  4. The refrigerant must be at least one year old

Explanation

Recycling for reuse in the same vehicle requires that the refrigerant pass through the recycling circuit and satisfy the applicable purity specification. Age, operating speed, and port choice do not establish purity. If the standard cannot be met, the refrigerant must be sent for reclamation.