Controlled clearing of a refrigerant opening

Abstract

A method for clearing a refrigerant fluid line opening in an air conditioning service fixture. The method includes establishing a pressure gradient between a fluid line branch encompassing the opening and the outside atmosphere, and utilizing the pressure gradient to purge air through the opening. Airflow between the opening and the fluid line is controlled to minimize the introduction of unwanted air into the air conditioning service fixture.

Description

Technical area

[0001] The present disclosure relates to routine operations of air conditioning service vehicles. More particularly, this disclosure relates to service vehicles used during the maintenance and servicing of vehicle air conditioning systems. background

[0002] Air conditioning service carts may be required by regulations to collect and identify samples of refrigerant used in vehicle systems during a drain phase of maintenance. This involves transferring refrigerant from the vehicle's air conditioning circuit to the service cart. Before being fed to an identification device, the refrigerant is drawn through a protective orifice. The protective orifice serves to protect the identification device and ensure optimal refrigerant purity during identification. The fluid paths of the service cart and vehicle also contain small amounts of oil to protect the function of the internal components of both the vehicle and the service cart and to extend their useful life. The oil is more viscous than refrigerant, and the protective orifice can become clogged with oil or residue with regular use of the service cart.The protective opening is designed to be non-serviceable to maintain the integrity of its protective features, preventing contamination and damage to the identification device. Routine operation of the service cart is desired, minimizing potential clogging of the protective opening caused by oil or residues in the fluid paths of the service cart and vehicle. Brief description

[0003] One aspect of the present disclosure relates to a refrigerant exchange method. The method comprises establishing a fluid connection between a service cart and a refrigerant circuit of a vehicle, the fluid connection comprising a high-pressure side connection and a suction-pressure side connection. The method further comprises reducing the fluid pressure in the fluid connection such that refrigerant in the refrigerant circuit is directed to a reservoir of the service cart for a draining operation. The method further comprises opening a solenoid associated with a refrigerant identification (RID) branch of the service cart a predetermined plurality of times while reduced fluid pressure prevails in the refrigerant circuit during the draining operation. The method further comprises closing the solenoid after a predetermined time window for each of the plurality of solenoid opening operations.The predetermined plurality of openings and the predetermined time windows are selected for purging an opening associated with the RID branch. In some embodiments, the solenoid may be subjected to between 2 and 5 openings. In some embodiments, one or more openings may comprise a predetermined time window with a duration between 3 and 7 seconds.

[0004] Another aspect of this disclosure relates to a refrigerant exchange method. The method comprises establishing fluid communication between a service cart and a refrigerant circuit of a vehicle, the fluid communication comprising a high-pressure side connection and a suction-side connection. The method further comprises reducing fluid pressure in the fluid communication such that refrigerant in the refrigerant circuit is directed to a reservoir of the service cart for a purge operation. The method further comprises opening a solenoid associated with a refrigerant identification (RID) branch of the service cart during a first time window while the refrigerant is purged into the reservoir such that a refrigerant sample accumulates in the RID branch of the service cart, and closing the solenoid after the sample has been identified or assessed for purity.The method further includes opening the solenoid a predetermined plurality of times while reduced fluid pressure prevails in the refrigerant circuit during the evacuation process, and closing the solenoid after a predetermined time window for each of the plurality of solenoid opening processes. The method further includes establishing a pressure differential between the service truck and the refrigerant circuit such that refrigerant is directed from the reservoir to the vehicle's refrigerant circuit in a refill process. The method further includes breaking the pressure differential after a vehicle-specified amount of refrigerant has been refilled from the reservoir into the refrigerant circuit. The predetermined plurality of opening processes and the predetermined time windows are selected for purging an orifice associated with the RID branch.In some embodiments, the solenoid may be subjected to between 2 and 5 opening operations. In some embodiments, one or more opening operations may comprise a predetermined time window with a duration between 3 and 7 seconds.

[0005] Another aspect of the present disclosure relates to a non-transitory computer-readable medium containing stored instructions that, when executed by a processor, cause the processor to perform the steps of a refrigerant exchange method. The method includes establishing fluid communication between a service cart and a refrigerant circuit of a vehicle, the fluid communication including a high-pressure side connection and a suction-pressure side connection. The method further includes reducing fluid pressure in the fluid communication such that refrigerant in the refrigerant circuit is directed to a reservoir of the service cart for a drain operation.The method further comprises opening a solenoid associated with a refrigerant identification (RID) branch of the service cart during a first time window while the refrigerant is being emptied into the reservoir, such that a refrigerant sample accumulates in the RID branch of the service cart, and closing the solenoid after the sample has been identified or assessed for purity. The method further comprises opening the solenoid a predetermined plurality of times while reduced fluid pressure prevails in the refrigerant circuit during the emptied operation, and closing the solenoid after a predetermined time window for each of the plurality of solenoid opening operations.The method further includes establishing a pressure differential between the service vehicle and the refrigerant circuit such that refrigerant is directed from the reservoir to the vehicle's refrigerant circuit in a refill operation. The method further includes breaking the pressure differential after a vehicle-specified amount of refrigerant has been refilled from the reservoir into the refrigerant circuit. The predetermined plurality of opening operations and the predetermined time windows are selected for purging an orifice associated with the RID branch. In some embodiments, the solenoid may be subjected to between 2 and 5 opening operations. In some embodiments, one or more opening operations may include a predetermined time window with a duration between 3 and 7 seconds.

[0006] The above aspects of the present disclosure and other aspects are explained in more detail below with reference to the accompanying drawings. Brief description of the drawings Fig. 1 is an illustration of a vehicle and a service cart during a service operation for an air conditioning system of the vehicle. Fig. 2 is an illustration of an air conditioning service vehicle. Fig. Figure 3 is a schematic diagram of a service vehicle refrigerant circuit. Fig. Figure 4 is a schematic representation with additional details of a refrigerant identification branch of the refrigerant flow circuit of Fig. 3 in close-up. Fig. 5 is a flowchart illustrating a method of clearing an opening of a refrigerant identification branch of a refrigerant flow circuit according to an embodiment of the teachings disclosed herein. Fig. 6 is a flowchart illustrating a method for draining and recharging refrigerant according to one embodiment of the teachings disclosed herein. Detailed description

[0007] The illustrated embodiments are disclosed with reference to the drawings. It should be understood, however, that the disclosed embodiments are intended to be merely examples that may be embodied in various and alternative forms. The figures are not necessarily to scale, and some features may be exaggerated or reduced to show details of particular components. The specific structural and functional details disclosed are not to be construed as limiting, but rather as a respective basis for teaching one skilled in the art how to practice the disclosed concepts.

[0008] Fig. 1 shows a typical use case in which a user 100 performs a fluid exchange operation for a vehicle 102 using a service cart 103. While in the illustrated embodiment, the fluid exchange operation of the service cart 103 is directed to the air conditioning system of the vehicle 102, other embodiments may be directed to other fluid exchange services without departing from the teachings disclosed herein. In the illustrated embodiment, refrigerant is moved between the vehicle 102 and the service cart 103 via a number of hoses 105 coupled at one end to the vehicle 102 and at the other end to the service cart 103. Each of the hoses 105 is coupled, in an assembled state, to the service cart 103 via a hose connector assembly 107.

[0009] Fig. 2 shows the service cart 103 and components thereof. The service cart 103 includes a console 201 that provides a user with displays and controls for the functions of the service cart 103. The chassis 203 of the service cart 103 supports a number of ports 205 that provide fluid communication with a storage tank 207 disposed at least partially within the chassis 203. In the illustrated embodiment, the ports 205 include a high-pressure side port and a suction-pressure side port that are used to exchange refrigerant between a vehicle (such as vehicle 102; see Fig. 1) and the service cart 103 are conventional; however, other embodiments may include other configurations without departing from the teachings disclosed herein. During servicing, the service cart 103 is operable to transfer refrigerant to and from the vehicle and storage tank 207 via the ports 205. This transfer is accomplished using pressure differentials in lines in fluid communication between refrigerant circuits of the serviced vehicle and the service cart 103.

[0010] Fig. 3 is a simplified schematic view of a representation of a refrigerant circuit 300 of a service cart (such as service cart 103; see Fig. 1, Fig. 2). The circuit 300 includes a main manifold 301, a purge manifold 303, and an injection manifold 305. The circuit 300 further includes a vacuum pump 307 suitable for creating pressure differentials in the fluid channels of the circuit 300. The circuit 300 further includes an oil drain tank 309. The circuit 300 further includes a compressor 311 suitable for initiating changes of state in the refrigerant as well as for initiating movement of the refrigerant in the circuit 300 in at least one direction. The vacuum pump 307 may be used to create pressure differentials that cause refrigerant to be moved with respect to other portions of the circuit 300 or with additional respect to external devices in fluid communication with the circuit 300 (e.g., the refrigerant circuit of an air conditioning system of a vehicle such as the vehicle 102; see Fig. 1) flows into or out of the storage tank 207 (see also Fig. 2). The compressor 311 may additionally facilitate movement of the refrigerant into or out of the storage tank 207 with respect to other portions of the circuit 300 or with additional reference to external devices in fluid communication with the circuit 300 (e.g., the refrigerant circuit of an air conditioning system of a vehicle such as the vehicle 102; see Fig. 1) initiate.

[0011] The circuit 300 includes additional features, including a portion thereof designated as the refrigerant identification (RID) branch 350. The RID branch 350 is in fluid communication with lines of the circuit 300 leading to the storage tank 207 and at least one of the ports 205. During circuit maintenance operations, the RID branch 350 serves to perform required sampling and identification functions of refrigerant used in a vehicle undergoing the maintenance operation. This sampling and identification operation is necessary to ensure that the correct refrigerant specified by a vehicle manufacturer is used, to ensure that the refrigerant used by the vehicle has a minimum purity during the maintenance operation, and to ensure compliance with any local legal requirements related to the maintenance operation.

[0012] The sampling and identification of refrigerant typically occurs during the purge phase of a maintenance operation. For the purposes of the present disclosure, "purge" refers to the process of transferring refrigerant from a vehicle's air conditioning circuit to storage tank 207. During purge, vacuum pump 307 lowers the internal pressure of the fluid lines of circuit 300 while the vehicle's air conditioning circuit is in fluid communication with ports 205. The resulting pressure differential initiates the initiation of refrigerant transfer. As refrigerant is transferred to storage tank 207, a portion of the purged refrigerant necessarily passes through RID branch 350 en route to storage tank 207. By allowing refrigerant to flow into RID branch 350 during purge, elements of RID branch 350 permit sampling and identification of the refrigerant.

[0013] Fig. Figure 4 is a close-up schematic of the elements of RID branch 350. RID branch 350 includes a refrigerant identification device (RID) 401. RID 401 includes a combination of fluid collection components and chemical analysis components to provide refrigerant identification and assess its purity. Refrigerant may enter RID branch 350 via activation of RID solenoid 403, which may be normally closed to optimize the transfer of refrigerant in main manifold 301 when a sample is not needed for the maintenance operation. When solenoid 403 is open, refrigerant may pass from main manifold 301 to RID 401 via RID line 405. In the illustrated embodiment, RID line 405 includes gas-tight hoses; however, other embodiments may include other constructions without departing from the teachings disclosed herein.

[0014] Since sampling and identification occur during draining, the pressure in the main manifold 301 is still close to vacuum, and the refrigerant sample can be expelled from the RID 401 by a pressure gradient between the RID 401 and the main manifold 301. The pressure gradient draws refrigerant from the RID branch 350 if the solenoid 403 remains open.

[0015] The fluid lines of the service cart contain materials other than refrigerant. In addition to contaminants and foreign matter that may be transferred from the vehicle into the fluid lines during emptying, the fluid lines may also contain a certain amount of oil to protect and maintain the internal components of the service cart 103, such as solenoids (including solenoid 403), check valves, fittings, seals, or other components that require oil to maintain their function. In addition, traces of air from sources external to the fluid lines may be detected in the fluid lines through normal use of the service cart 103.

[0016] The RID 401 contains sensitive electronic and other components. Thus, it is important to minimize contaminants in the refrigerant during identification to ensure both correct refrigerant identification and purity, as well as to protect the components of the RID 401. For this reason, a protective orifice 407 is provided above the RID line 405 to minimize the transfer of any non-refrigerant material between the RID 401 and the main manifold 301. The orifice 407 includes a "pinhole" design to facilitate this filtration by providing a passage through which primarily refrigerant, but not oil or other contaminants in the refrigerant, can pass.

[0017] Because opening 407 comprises such a small passage, oil or other contaminants may cause the passage to become blocked during repeated normal use of service cart 103, making refrigerant sampling and identification less efficient and more time-consuming. To address these potential blockages of opening 407, solenoid 403 may undergo one or more controlled opening operations after the refrigerant has been removed from RID 401 and RID line 405. The controlled opening of solenoid 403 may result in a pressure differential between RID 401 and the lines in main manifold 301 shortly before the end of the purge phase because the pressure in main manifold 301 is still close to vacuum. To generate the pressure gradient, normal air pressure can be introduced from outside the RID 401 by allowing a small amount of air 408 to pass through an RID filter 409 into the RID 401.The RID filter 409 is designed to allow air flow but prevent other external contaminants from entering the RID 401. This pressure differential can be used to apply pressure across the orifice 407 toward the solenoid 403 if the orifice 407 is completely or partially blocked. If there is no blockage, a small amount of ambient air may enter the fluid lines, but excess air can be vented from the system after the end of the drain using a conventional venting mechanism of the storage tank 207 (see ). Fig. 2; Fig. 3).

[0018] The timing of the openings of solenoid 403 can be controlled to optimize the pressure drop used to purge or clear opening 407 while minimizing the introduction of outside air into the fluid lines. In the illustrated embodiment, solenoid 403 can be subjected to a predetermined number of openings, interrupted by closures of solenoid 403. After the opening, solenoid 403 can remain open for a predetermined time window for each of the openings. For example, and not by way of limitation, solenoid 403 can be subjected to between 2 and 5 openings during purging after identification is complete, and each of the openings can be followed by a predetermined time window lasting 3 to 7 seconds.In the illustrated embodiment, the solenoid 403 may undergo three opening operations, with each opening operation lasting a predetermined time window of 5 seconds; however, other embodiments may include other arrangements or configurations without departing from the teachings disclosed herein. In the illustrated embodiment, each of the opening operations is followed by a time window that is identical to all other time windows during which the solenoid 403 remains open; however, other embodiments may include other predetermined time windows for one or more opening operations without departing from the teachings disclosed herein.In different embodiments, different numbers of openings or time window durations may be used to provide optimal conditions for a particular type of refrigerant or a particular type of oil used by a service truck without departing from the teachings disclosed herein.

[0019] In the illustrated embodiment, the control of the solenoid 403 can be performed by a processor associated with the service cart. The processor (not shown) of the service cart 103 (see Fig. 1; Fig. 2) can execute instructions stored in a non-transitory computer-readable medium (not shown) associated with the service cart, such as memory in data communication with the processor.

[0020] Fig. 5 is a flowchart illustrating a method for performing opening operations for a solenoid (such as solenoid 403; see Fig. 4), where a refrigerant identification branch (RID branch) (such as RID branch 350; see Fig. 3, Fig. 4) from other fluid lines (such as main distributor 301; see Fig. 3, Fig. 4) a fluid exchange device such as a service cart (such as service cart 103; see Fig. 1, Fig. 2) while performing a maintenance operation for a vehicle (such as vehicle 102; see Fig. 1) is separated.

[0021] The method begins at step 500 with the fluid connection between the vehicle and the service cart. The fluid connection is established by connecting hoses (such as hoses 105; see Fig. 1) between service car connections (such as connections 205; see Fig. 2) and connections of the vehicle's air conditioning system. In some embodiments, the fluid connection can additionally be established by opening solenoids in the service vehicle's fluid circuit, which control the flow of material from the connections to other elements of the circuit.

[0022] After establishing the fluid connection in step 500, the method proceeds to step 502, in which the pressure in the fluid lines of the service cart is reduced either by a pump (such as vacuum pump 307; see Fig. 3) or a compressor (such as compressor 311; see Fig. 3). The pressure reduction in the fluid lines of the service trolley causes a pressure differential between the service trolley and the vehicle, which makes it difficult to empty or transfer fluid from the vehicle into a tank of the service trolley (such as tank 207; see Fig. 2) is initiated. After a period of time during the evacuation, the method proceeds to step 504, where a solenoid associated with a refrigerant identification device (RID) undergoes an opening operation. In the illustrated embodiment, this solenoid opening operation (referred to as the "RID solenoid" for clarity) may be to draw refrigerant into the RID for sampling and identification, or it may occur after an intermediate sampling and identification step without departing from the teachings disclosed herein. After the RID solenoid closes, the method proceeds to step 506, where it is determined whether any additional RID solenoid opening operations are scheduled. Repeated opening operations may be to provide additional maintenance or protection functions of the service cart, such as clearing a potentially clogged opening (such as opening 407; see Fig. 4). If additional opening operations are scheduled, the method proceeds to step 508 and waits for a predetermined time window to expire before returning to step 504 to reopen the RID solenoid. In the illustrated embodiment, each iteration of step 504 may include opening the RID solenoid for the same period of time; however, other embodiments may include other arrangements without departing from the teachings disclosed herein.

[0023] After performing the entire predetermined number of RID solenoid opening operations in step 506, the method proceeds to step 510 and ends.

[0024] Fig. 6 is a flowchart illustrating a method for emptying and recharging refrigerant between a service device (such as service cart 103; see Fig. 1, Fig. 2) and a vehicle (such as vehicle 102; see Fig. 2).

[0025] Fig. 5 is a flowchart illustrating a method for performing opening operations for a solenoid (such as solenoid 403; see Fig. 4), where a refrigerant identification branch (RID branch) (such as RID branch 350; see Fig. 3, Fig. 4) from other fluid lines (such as main distributor 301; see Fig. 3, Fig. 4) a fluid exchange device such as a service cart (such as service cart 103; see Fig. 1, Fig. 2) while performing a maintenance operation for a vehicle (such as vehicle 102; see Fig. 1) is separated.

[0026] The method begins at step 600 with the fluid connection between the vehicle and the service device. The fluid connection may be established by connecting hoses (such as hoses 105; see Fig. 1) between service car connections (such as connections 205; see Fig. 2) and connections of the vehicle's air conditioning system. In some embodiments, the fluid connection can be established by opening solenoids in the service vehicle's fluid circuit, which control the flow of material from the connections to other elements of the circuit.

[0027] After establishing the fluid connection in step 600, the method proceeds to step 602, in which the pressure in the fluid lines of the service cart is reduced either by a pump (such as vacuum pump 307; see Fig. 3) or a compressor (such as compressor 311; see Fig. 3). The pressure reduction in the fluid lines of the service vehicle causes a pressure differential between the service vehicle and the vehicle, causing refrigerant to drain from the vehicle into a tank of the service device (such as tank 207; see Fig. 2) is initiated.

[0028] After a period of time during the purge, the method proceeds to step 604, where an identification substep is performed. During the identification substep, a solenoid associated with a component acting as a refrigerant identification device (RID) of the service device opens during a first time window to allow a sample-sized amount of refrigerant to be injected into an RID branch (such as RID branch 350; see Fig. 3, Fig. 4) of the service device. This solenoid may be referred to as the "RID" solenoid for clarity. During this evacuation phase, the pressure in the RID branch is lower than in the vehicle's fluid lines, and refrigerant flows through the RID branch into the RID. During this transfer for sampling purposes, the refrigerant passes through a protective orifice (such as orifice 407; see Fig. 4) designed to prevent oil, contaminants, air, or other contaminants from entering the RID. After the RID completes an identification or purity assessment of the refrigerant, the RID solenoid reopens, and a pressure differential is created between the RID and the service device's storage tank, expelling the refrigerant from the RID branch.

[0029] After the refrigerant is expelled from the RID branch, the protective opening may be blocked or clogged by non-refrigerant material in the service cart fluid lines. To compensate, the method proceeds to step 606 to initiate an iterative clearing substep. Clearing begins by performing an RID solenoid opening procedure, opening the RID solenoid while the service device fluid line is still at very low pressure. This very low pressure creates a pressure differential between the RID branch and the outside environment, which creates a controlled airflow through the protective opening toward the service device fluid line. The opening procedure includes opening the RID solenoid and maintaining its open state for a predetermined time window.In the illustrated embodiment, the predetermined time window can be between 2 and 5 seconds, and can be approximately a 3-second window. The predetermined time window is selected to allow some air to move through the protective opening for clearing, but not so much that more air is added to the fluid line than can be vented within normal operation of the storage tank. After the predetermined time window has elapsed, the solenoid is closed.

[0030] The method then proceeds to step 608. Additional opening operations may be desired to optimize the clearing of the protective opening. If additional opening operations are planned, the method proceeds to step 610 and waits for a predetermined time window to elapse before returning to step 606 to reopen the RID solenoid. In the illustrated embodiment, each iteration of step 606 may include opening the RID solenoid for the same period of time; however, other embodiments may include other arrangements without departing from the teachings disclosed herein. After completing a desired number of opening operation iterations, the air introduced into the fluid lines by the RID solenoid opening operations may be vented from the storage tank.

[0031] After performing the entire predetermined number of RID solenoid opening operations at step 608, the method proceeds to step 612, where a pressure differential is created in the service device fluid lines such that the pressure in the service device is higher than in the vehicle fluid lines. This pressure differential causes refrigerant to flow from the storage tank back into the vehicle fluid lines in a recharge operation. The recharge is monitored based on the weight of the storage tank. When the vehicle has been recharged with a specific amount of refrigerant, the method may proceed to step 614 and end. The specific amount of refrigerant for the recharge is specified by the vehicle air conditioning manufacturer and varies depending on the vehicle make and model.

[0032] The implementation of the procedure by Fig.6 may also be controlled autonomously by a processor executing instructions stored in a non-transitory computer-readable medium.

[0033] In the illustrated embodiment, the processor may be embodied as a specialized processor of the service device; however, other embodiments may include other configurations without departing from the teachings disclosed herein. The processor may be embodied as a mobile processing device, a smartphone, a tablet, a laptop, a portable computing device, a desktop computer, a personal digital assistant (PDA) device, a handheld processor device, a specialized processor device, a system of processors distributed over a network, a system of processors configured for wired or wireless communication, or any other alternative embodiment known to those of ordinary skill in the art.

[0034] In the illustrated embodiment, the non-transitory computer-readable medium may be embodied as a memory of the service device in data communication with the specialized processor; however, other embodiments may include other configurations without departing from the teachings disclosed herein. Such non-transitory computer-readable storage media or machine-readable media may be any available media embodied in hardware or physical form that can be accessed by a general-purpose or special-purpose computer.By way of example, and not limitation, such non-transitory computer-readable storage media or machine-readable media may include random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), optical disk storage, magnetic disk storage, linear magnetic data storage, magnetic storage devices, flash memory, or any other medium capable of transporting or storing desired program code means in the form of computer-executable instructions or data structures. Combinations of the above should also be included within the scope of non-transitory computer-readable storage media or machine-readable media.

[0035] While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms of the disclosed apparatus and method. Rather, the language used in the specification is descriptive and not limiting, and it is understood that various changes may be made without departing from the spirit and scope of the disclosure as claimed. The features of various implementation embodiments may be combined to form further embodiments of the disclosed concepts.

Claims

A refrigerant exchange method comprising: establishing a fluid connection between a service cart and a refrigerant circuit of a vehicle, the fluid connection comprising a high-pressure side connection and a suction-pressure side connection; reducing the fluid pressure in the fluid connection such that refrigerant in the refrigerant circuit is directed to a reservoir of the service cart for a draining operation; opening a solenoid associated with a refrigerant identification (RID) branch of the service cart a predetermined plurality of times while reduced fluid pressure prevails in the refrigerant circuit during the draining operation; and closing the solenoid after a predetermined time window for each of the plurality of solenoid opening operations; wherein the predetermined plurality of opening operations and the predetermined time windows are selected for purging an opening associated with the RID branch. Refrigerant exchange method according to claim 1, wherein the solenoid is subjected to between 2 and 5 opening operations during the evacuation. A refrigerant exchange method according to claim 2, wherein the solenoid is subjected to 3 opening operations during the discharge. The refrigerant exchanging method according to claim 1, wherein the predetermined window has the same time duration for each of the corresponding opening operations of the solenoid. The refrigerant exchange method of claim 1, wherein the predetermined time window has a different time duration for at least one of the plurality of opening operations of the solenoid. The refrigerant exchange method according to claim 1, wherein the solenoid is opened for a predetermined time window of 3-7 seconds during the evacuation. The refrigerant exchange method of claim 6, wherein each of the plurality of opening operations during the evacuation lasts a window of 5 seconds. A refrigerant exchange method according to claim 7, wherein the solenoid is subjected to 3 opening operations during the evacuation. A refrigerant exchange method comprising: establishing a fluid connection between a service cart and a refrigerant circuit of a vehicle, the fluid connection comprising a high-pressure side connection and a suction-pressure side connection; reducing the fluid pressure in the fluid connection so that refrigerant in the refrigerant circuit is directed to a reservoir of the service cart for a draining operation; opening a solenoid associated with a refrigerant identification (RID) branch of the service cart while the refrigerant is drained into the reservoir during a first time window so that a refrigerant sample accumulates in the RID branch of the service cart; closing the solenoid; opening the solenoid a predetermined plurality of times while reduced fluid pressure prevails in the refrigerant circuit during the draining operation;Closing the solenoid after a predetermined time window for each of the plurality of solenoid opening operations, establishing a pressure differential between the service vehicle and the refrigerant circuit so that refrigerant is directed from the reservoir to the vehicle's refrigerant circuit in a refilling operation, and breaking the pressure differential after a refrigerant quantity specified for the vehicle has been refilled from the reservoir into the refrigerant circuit, wherein the predetermined plurality of opening operations and the predetermined time windows are selected for purging an opening associated with the RID branch. Refrigerant exchange method according to claim 9, wherein the solenoid is subjected to between 2 and 5 opening operations during the evacuation. A refrigerant exchange method according to claim 10, wherein the solenoid is subjected to 3 opening operations during the evacuation. The refrigerant exchanging method according to claim 9, wherein the predetermined window has the same time duration for each of the corresponding opening operations of the solenoid. The refrigerant exchange method of claim 9, wherein the predetermined time window has a different time duration for at least one of the plurality of opening operations of the solenoid. Refrigerant exchange method according to claim 9, wherein the solenoid is opened for a predetermined time window of 3 - 7 seconds during the evacuation. The refrigerant exchange method of claim 14, wherein each of the plurality of opening operations during the evacuation lasts a window of 5 seconds. A refrigerant exchange method according to claim 15, wherein the solenoid is subjected to 3 opening operations during the evacuation. A non-transitory computer-readable medium containing stored instructions that, when executed by a processor associated with a service cart, cause the processor to perform the following steps: establishing fluid communication between the service cart and a refrigerant circuit of a vehicle, the fluid communication comprising a high-pressure side connection and a suction-pressure side connection; lowering the fluid pressure in the fluid communication so that refrigerant in the refrigerant circuit is directed to a reservoir of the service cart for a draining operation; opening a solenoid associated with a refrigerant identification (RID) branch of the service cart while draining the refrigerant into the reservoir during a first time window so that a sample amount of refrigerant accumulates in the RID branch of the service cart; closing the solenoid; opening the solenoid a predetermined plurality of times;while reduced fluid pressure prevails in the refrigerant circuit during the emptying process, closing the solenoid after a predetermined time window for each of the plurality of solenoid opening operations, establishing a pressure differential between the service vehicle and the refrigerant circuit so that refrigerant is directed from the reservoir to the vehicle's refrigerant circuit in a refilling operation, and breaking the pressure differential after a refrigerant quantity specified for the vehicle has been refilled from the reservoir into the refrigerant circuit, wherein the predetermined plurality of opening operations and the predetermined time windows are selected for purging an opening associated with the RID branch. The refrigerant exchange method of claim 17, wherein the predetermined time window has a different time duration for at least one of the plurality of opening operations of the solenoid. The refrigerant exchange method of claim 17, wherein each of the plurality of opening operations during the evacuation lasts a window of 5 seconds. A refrigerant exchange method according to claim 19, wherein the solenoid is subjected to 3 opening operations during the evacuation.

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