USRE32451E - Weight-monitored air-conditioner charging station - Google Patents

Referring to FIGS. 1 and 2 of the drawing, there is shown a

10 which includes a

11, mounted for mobility on

12, and surmounted by a

13.

The

11 is provided with

14 and with hinged

15 and 16 which provide access to the interior of the cabinet, when opened. In FIG. 1, portions of these doors have been broken away to show a motorized

17 mounted interiorly of the cabinet on one side of the base thereof. On the other side of the base of the cabinet interior there is mounted a

18 having a

19 on which is secured a pressurized refrigerant canister or

20 by means of a suitable

21. Also mounted on the

19 and secured thereto by a suitable

22 is a pressurized oil cylinder or

23. Each of the canisters is provided with its own conventional shut-off valve (not shown) which, when opened, permits the refrigerant reservoir to communicate through

24 with a

25 and permits the oil reservoir to communicate through

26 with a

27. A

28 provides communication from the vacuum pump to a

29.

As best seen in FIG. 2, the

25 communicates with a

30 through

31 and communicates with a

32 through

33.

The

27 is provided with a

34 by means of which the pressurized oil can also be directed to the

30, by joinder with the

31.

The

29 also communicates with

30 through a

36, by joinder with the

31.

A

35 is provided for connecting a hose to the high pressure side of the refrigeration system being serviced. A

37 leads from this

35 to the interior of the

11. A

37a connects the

37 to a

38. Operationally, the

37 is used for "dumping" the fluid contents of the air conditioner being serviced prior to evacuation, through a

55a, as well as for monitoring system pressure via

38 during charging.

Optionally another

39, branching from the

31, can be provided for communication with an

40 for non-automated low pressure discharge, such as pressurizing the oil cylinder or discharging a small canister.

An

41 which incorporates a microprocessor sequencing unit is operatively connected to the various components previously described, receiving signals from

18 and manual controls, and sending signals to control valves; the sequencing unit also serves to energize a digital weight

42 on the

13.

An electronic signal in the form of a buzzer or

43 is also mounted on the interior of the control panel and operatively connected to the

41.

A

44 is secured to the back of the control panel. In FIG. 2 large portions of the

44 have been broken away to show the above-described component locations.

As best shown in FIG. 3 of the drawing, the

18 is of the type which produces an output signal proportional to weight; preferably, it is of the electrical reluctance type which utilizes a current-carrying

45 and a movably-mounted

46 projecting into the center of the coil. The

46 is secured by an adjustable

47 to a

48 to which the

19 is fixedly secured by a

49.

The

48 is yieldably mounted by a parallelogram arrangement of

50. Two horizontally-spaced

50 extend horizontally from the upper portion of the beam to securement with the upper portion of an L-

51. Another pair of spaced

50 extend horizontally from the lower portion of the beam, parallel to the

50, to the lower portion of the

51. The base 51 also serves as an anchor for a

52 to which the

45 is fixedly secured.

The resilient parallelogram mounting of the

48 permits substantially linear movement of the beam in response to changes in load on the

19. The movement of the beam is directly transmitted to the armature or

46 and the electromagnetic changes effected by its interaction with the

45 are transmitted to and sensed by the

41. An

53 is mounted on the

48 for abutment with the

51, so as to limit movement of the beam to its operating range and prevent excessive distortion or deformation of the movable beam assembly.

The operation of the charging station is as follows, using the microprocessor sequencing unit of

41 and the manual controls are illustrated in FIG. 1 of the drawing. Basically, the re-charging procedure consists of emptying and evacuating the air-conditioning or refrigerating apparatus, as necessary, then charging lubricating oil into the apparatus, and then charging refrigerant into the apparatus. The detailed hook-ups and quantities for accomplishing the foregoing are well-known in the art and therefore require no further explanation.

As best seen in FIG. 1, the

13 carries an "on-off"

54 which is manipulated to energize the charging station's electrical and electronic components from a conventional power source. There is also a bleed

55 which is turned to open

55a to discharge or "dump" the fluid contents of the air-conditioner through the

37 before evacuation. A discharge catch tray (not shown) is provided under the cabinet base, equipped with steel wool to entrap the oil carried with the discharging refrigerant.

A

56, calibrated in minutes, serves to hold open the

29 for a selected time interval. The

17 will operate during the selected time interval, nominally ten minutes for the usual size of passenger vehicle air-conditioner, and then evacuation should be complete, as evidenced by a reading of 30 inches Hg on the

32. During evacuation, no other functions of the charging station will be performed, even though charging quantities have been pre-set for the oil and refrigerant charges. An

57 remains lighted until the timed evacuation is completed.

The charging settings can be selected either during evacuation or upon completion of evacuation, as desired. First, a setting

58, which is calibrated in pounds, is set to the selected weight of refrigerant to be charged. As this control knob is manipulated, the changing settings are visible in the

42, in pounds and ounces avoirdupois, accurate to 0.2 ounces, so that an extremely precise setting to a decimal fraction of an ounce can be established. When the desired setting is achieved, a

59 is momentarily depressed to feed this setting to the computer memory, which acknowledges receipt by initiating an audible "beep". As will appear more fully hereinafter, the

59 also serves as a sequence interrupter during the charging cycles. The operation of the

59 clears the refrigerant setting from the

42.

Thereafter, another setting

60, calibrated in fluid ounces, is set to the desired volume of oil to be charged, which is similarly displayed in ounces on the

42. When the desired oil setting is achieved, a "Start" switch or

63 on the control panel is momentarily depressed to feed this setting to the computer memory. Receipt of the oil setting is acknowledged by an audible "beep".

If the refrigerant and oil charge setting have been made during the timed evacuation interval, then upon completion of evacuation, the

57 goes out, a "beep" signal is heard, an

61 is actuated, the

27 opens, and oil under pressure is automatically charged into the air conditioner. During this oil charging cycle, the

42 will continually be changing to reflect the remaining quantity of charge yet to be made; i.e., the digital display approaches a zero reading as the computer monitors the weight loss indicated by weighing

18.

It is to be noted that it has become a standard practice in the art to use fluid ounces as the quantitative measure of the oil charge. In order to conform to this practice, the oil charge is set and displayed in fluid ounce measure. However, as the

18 senses only weight, the computer module is programmed to convert the oil charge setting to ounces of weight and monitors the charge in a weight-equivalent to the fluid ounce setting.

When a zero reading is attained on the

42, indicating that the desired weight-equivalent charge of oil has been dispensed, the

27 closes. However, the computer module continues to monitor the

18 at short intervals, e.g. 11/3 seconds, several times, say five times, to confirm that the

18 is stable and that the zero reading is, in fact, true. If a false zero reading has been momentarily attained as a result of

18 being disturbed by movement of the charging station or by someone or something bumping into it, then the zero reading will not be confirmed and

27 will open again to continue the oil charge until a true zero reading, indicating completion of the charge, is attained, and

27 closes.

After completion of the oil charge, an automatic short timed pulse of chase refrigerant is directed through

24,

31, and out

30 to clear the lines of retained or residual oil, so that the full charge of oil is dispensed into the air-conditioner. Signal light 61 is extinguished, and a "beep" sound is heard signalling completion of the oil charge cycle and automatic starting of the refrigerant charge cycle.

At the initiation of the refrigerant charge cycle, the

42 is cleared and the previously set selected weight of refrigerant charge is displayed. A

62 lights up and

25 opens to charge pressurized refrigerant into the air-conditioner.

In the same manner explained above, the computer module monitors the weight loss on

18, continuously indicates on the

42 the remaining weight of refrigerant yet to be dispensed, confirms the zero reading by repeated discrete monitoring of

18 at short time intervals, reopens

25 to continue dispensing if a false zero reading was indicated by

18, and finally closes

25, de-energizes signal light 62, and sounds an audible "beep" signal that the operation has been completed.

There may be circumstances when it is considered desirable to complete the evacuation cycle and visually monitor the readings on the

32, without automatically initiating the subsequent charging cycles. If such is desired, then the operator simply postpones entering the oil and refrigerant quantity settings until after evacuation has been satisfactorily completed. The charging cycles are then initiated by momentary depression of the "Start"

63 on the control panel, and the automatic operation commences.

There may also be circumstances when it is considered desirable to omit the evacuation cycle. In such cases the operator proceeds directly to making the refrigerant and oil quantity settings. The charging cycles are then initiated by momentary depression of the "Start"

63, and automatic operation commences.

Whether the charging cycles are automatically initiated upon completion of the evacuation cycle, or directly initiated independently of evacuation by pressing

63, the

41 is programmed to start reading or monitoring the load on

18 at the start of the oil charging cycle, not sooner. Thus, any inaccuracy or changes in the scale readings which may occur due to metal fatigue or temperature drift in the

18 over a period of time, or even in the relatively short time span of the evacuation phase, are ignored and eliminated. Thereby, the measure of charge, as determined by the targeted weight loss or load differential on

18, can be attained with extreme accuracy.

The

41 not only continuously monitors the weight loss on

18 during each of the charging cycles, it also monitors the rate of weight loss so that any interruption or excessive slowdown in the transfer of the charge to the air-conditioner causes an audible "beep" alarm signal to be sounded. Such restriction or interruption of flow to the air-conditioner is ordinarily the result of an inadequate supply of pressurized oil or refrigerant in the charging

20 or 23 or may result from the existence of an inadequate pressure differential between the charging system and the air-conditioner.

When this distinctive alarm is sounded, the operator can visually observe which charging cycle, whether oil or refrigerant, is affected by noting which signal light 61 or 62 is lit. The operator can then place the entire charging system in "Hold" status, by momentarily

59--which will cause closing of the

25 or 27, as the case may be. The operator can then check the

20 or 23 and replace it, if necessary, with a full canister. It will be apparent that this replacement will establish an entirely new and different load or weight on

18. But, inasmuch as the charging system herein described monitors loss of weight on

18 rather than weight directly, when the charging cycle is removed from "Hold" and restarted by momentary depression of

63, the

41 continues its monitoring at exactly the same point in the cycle where it was placed on "Hold". Thus, the computer module will concern itself only with the remaining weight differential required to complete the charge, despite the intervening change in load on

18; no re-setting of the quantity of charge is required. Similarly, any adjustments required to be made to the air-conditioner to correct the inadequate pressure differential problem will not require re-setting of the charge quantities to re-start the charging cycles from the point of interruption.

For example, it has been determined that the flow interruption alarm should be actuated if the charging rate of oil is more than 30 seconds per ounce or if the charging rate of refrigerant is more than one minute per pound, although other perameters could be established, as desired, and programmed into

41.

Additional safety features for the charging system relate to excessive discharge pressure and to inadvertent start-up of the vacuum system during operation of a charge cycle. If the

56 is manipulated during a charging cycle, an alarm sounds and the charging cycle is automatically terminated. Similarly, if the discharge pressure reaches a dangerous level, e.g., 275 psi, as sensed by a high pressure cut-

64, the alarm sounds and the charging cycle is automatically terminated. In either circumstance, the situation must be investigated and corrected. Then the whole operative cycle of the charging station must be re-initiated, including the steps of setting the quantities of oil and refrigerant to be charged into the air-conditioner.

1. In an air-conditioner charging station, the combination of:

(a) a powered vacuum pump for evacuation of an air-conditioner;

(b) a reservoir of oil under pressure,

(c) a reservoir of refrigerant under pressure,

(d) conduit means and electrically operated valve means for selectively connecting said pump and each of said reservoirs to the air-conditioner to be serviced,

(e) weighing means, common to both said reservoirs, for sensing the combined weight thereof and for producing an output signal proportional to the combined weights of said reservoirs,

(f) electronic sequencing means operatively associated with said valve means and said weighing means for receiving said output signal for monitoring weight loss from said reservoirs as oil or refrigerant is discharged therefrom and for generating signals for controlling said valve means,

(g) adjustable weight differential input means operatively connected to said sequencing means for introducing into said sequencing means selected values representative of preselected weight of refrigerant and oil to be discharged from said reservoirs, and

(h) means for initiating operation of said sequencing means to receive and monitor said weighing means output signal and to provide signals to said control valve means for sequentially charging a preselected weight of oil from said oil reservoir and then a preselected weight of refrigerant from said refrigerant reservoir into the air-conditioner.

2. A combination as defined in claim 1, and further including means responsive to completion of said oil charge for initiating a short timed pulse of refrigerant charge to chase residual oil from said charging station into the air-conditioner.

3. A combination as defined in claim 1, and further including a digital visual display unit for said selected weight differential input means, and wherein said sequencing means senses the weight loss in said reservoirs during said charging cycles and said display unit continuously indicates said weight loss.

4. A combination as defined in claim 3, wherein said sensing of weight loss by said sequencing means is continuous until said preselected weight of charge is indicated as having been dispensed, and including multiple discrete sensing of said weight loss at timed intervals in response to completion of said continuous sensing, whereby to obtain confirmation of stabilized attainment of said pre-selected weight of charge prior to cessation of the charging cycle.

5. A combination as defined in claim 3, wherein said sequencing means senses both the weight loss and the rate of weight loss in said reservoirs, and including signal means actuated in response to a separate predetermined parameter of rate of weight loss for each of said reservoirs.

6. A combination as defined in claim 3, including manually-actuated interrupter means for said .[.microprocessor.]. sequencing means, whereby sequencing can be arrested at any step thereof and restarted from the point of arrest.

7. A combination as defined in claim 1, and further including a high pressure cut-out switch for sensing discharge pressure, said sequencing means generating signals for terminating charging upon sensing of a high pressure by said high pressure cut-out switch.

8. An air-conditioner charging station for charging refrigerant into an air-conditioner comprising:

(a) a powered vacuum pump for evacuation of an air-conditioner,

(b) a reservoir of oil under pressure,

(c) a reservoir of refrigerant under pressure,

(d) conduit means and electrically operated valve means for selectively connecting or disconnecting said vacuum pump and each of said reservoirs to the air-conditioner to be serviced,

(e) weighing means for sensing the weight of said reservoirs and for substantially continually producing an output signal proportional thereto as weight is decreased during charging,

(f) electronic sequencing means including adjustable oil and refrigerant preselected weight differential input means operatively associated with said valve means and said weighing means for receiving said output signal from said weighing means for monitoring weight loss as oil or refrigerant is discharged from a said reservoir into said air conditioner and for generating signals, including a signal to a said valve means for disconnecting a said reservoir from the air-conditioner upon receiving a signal indicating that the preselected weight of charge has been dispensed,

(g) means for initiating operation of said sequencing means for sequentially charging a preselected weight of oil from said oil reservoir and then a preselected weight of refrigerant from said refrigerant reservoir into the air-conditioner,

9. A combination as defined in claim 8, wherein said sequencing means senses rate of weight loss in said reservoirs, and including signal means actuated in response to a separate, predetermined parameter of rate of weight loss for each of said reservoirs.

10. A combination as defined in claim 9, and further including a high pressure cut-out switch for sensing discharge pressure, said sequencing means generating signals for terminating charging upon sensing of a high pressure by said high pressure cut-out switch.

11. An air-conditioner charging station for charging refrigerant into an air-conditioner comprising:

(a) a powered vacuum pump for evacuation of an air-conditioner,

(b) a reservoir of oil under pressure,

(c) a reservoir of refrigerant under pressure,

(d) conduit means and electrically operated valve means for selectively connecting or disconnecting said vacuum pump and each of said reservoirs to the air-conditioner to be charged,

(e) weighing means for sensing the weight of said reservoirs and for substantially continually producing an output signal proportional thereto as weight is decreased during servicing,

(f) electronic sequencing means operative associated with said valve means and said weighing means for monitoring weight loss and rate of weight loss as oil or refrigerant is discharged from a said reservoir into said air-conditioner,

(g) adjustable weight differential input means operatively connected to said sequencing unit,

(h) means for initiating operation of said sequencing means for sequentially charging a preselected weight of oil from said oil reservoir and then a preselected weight of refrigerant from said refrigerant reservoir into the air-conditioner, and

(i) signal means actuated in response to a separate predetermined parameter of rate of weight loss for each of said reservoirs for indicating an inadequate supply of pressurized oil or refrigerant in the charging reservoirs or the existence of an inadequate pressure differential between the charging system and the air-conditioner.

12. A combination as defined in claim 11, and further including a high pressure cut-out switch for sensing discharge pressure, said sequencing means generating signals for terminating charging upon sensing of a high pressure by said high pressure cut-out switch. .Iadd.

13. In an air-conditioner charging station, the combination of:

(a) a powered vacuum pump for evacuation of an air-conditioner;

(b) a reservoir of refrigerant under pressure,

(c) conduit means and electrically operated valve means for selectively connecting said pump and said reservoir to the air-conditioner to be serviced,

(d) weighing means for sensing the weight of said reservoir and for producing an output signal proportional to the weight of said reservoir,

(e) electronic sequencing means operatively associated with said valve means and said weighing means for receiving said output signal for monitoring weight loss from said reservoir as refrigerant is discharged therefrom and for generating signals for controlling said valve means,

(f) adjustable weight differential input means operatively connected to said sequencing means for introducing into said sequencing means a selected value representative of a preselected weight of refrigerant to be discharged from said reservoir,

(g) means for initiating operation of said sequencing means to receive and monitor said weighing means output signal and to provide signals to said control valve means for charging a preselected weight of refrigerant from said refrigerant reservoir into the air-conditioner,

(h) a digital visual display unit for said selected weight differential means,

(i) wherein said sequencing means senses the weight loss in said reservoir during said charging cycle and said display unit continuously indicates said weight loss, and

(j) wherein said sequencing means senses both the weight loss and the rate of weight loss in said reservoir, and

(k) signal means actuated in response to a separate predetermined parameter of rate of weight loss for said reservoir. .Iaddend. .Iadd.

14. A combination as defined in claim 13, wherein said sensing of weight loss by said sequencing means is continuous until said preselected weight of charge is indicated as having been dispensed, and including multiple discreet sensing of said weight loss at timed intervals in response to completion of said continuous sensing, whereby to obtain confirmation of stabilized attainment of said pre-selected weight of charge prior to cessation of the charging cycle. .Iaddend. .Iadd.15. A combination as defined in claim 13, including manually-actuated interrupter means for said sequencing means, whereby sequencing can be arrested at any step thereof and restarted from the point of arrest. .Iaddend. .Iadd.16. A combination as defined in claim 13, and further including a high pressure cut-out switch for sensing discharge pressure, said sequencing means generating signals for terminating charging upon sensing of a high pressure by said high pressure cut-out switch. .Iaddend. .Iadd.17. An air-conditioner charging station for charging refrigerant into an air-conditioner comprising:

(a) a powered vacuum pump for evacuation of an air-conditioner,

(b) a reservoir of refrigerant under pressure,

(c) conduit means and electrically operated valve means for selectively connecting or disconnecting said vacuum pump and said reservoir to the air-conditioner to be serviced,

(d) weighing means for sensing the weight of said reservoir and for substantially continually producing an output signal proportional thereto as weight is decreased during charging,

(e) electronic sequencing means including adjustable refrigerant preselected weight differential input means operatively associated with said valve means and said weighing means for receiving said output signal from said weighing means for monitoring weight loss as refrigerant is discharged from said reservoir into said air-conditioner and for generating signals, including a signal to said valve means for disconnecting said reservoir from the air-conditioner upon receiving a signal indicating that the preselected weight of charge has been dispensed,

(f) means for initiating operation of said sequencing means,

(g) said electronic sequencing means including means for sensing weight loss after the generation of said signal for disconnecting said reservoir at multiple discreet timed intervals and for generating a signal to the said valve means for connecting said reservoir to the air-conditioner upon receiving a signal that a false signal of dispensed weight change was received,

whereby to obtain confirmation of stabilized attainment of said preselected

weight change. .Iaddend. .Iadd.18. A combination as defined in claim 17, wherein said sequencing means senses rate of weight loss in said reservoir, and including signal means actuated in response to a separate, predetermined parameter of rate of weight loss for said reservoir. .Iaddend. .Iadd.19. A combination as defined in claim 17, and further including a high pressure cut-out switch for sensing discharge pressure, said sequencing means generating signals for terminating charging upon sensing of a high pressure by said high pressure cut-out switch. .Iaddend. .Iadd.20. In an air-conditioner charging station, the combination of:

(a) a reservoir of refrigerant under pressure,

(b) conduit means and electrically operated valve means for selectively connecting said reservoir to the air-conditioner to be serviced,

(c) weighing means for sensing the weight of said reservoir and for producing an output signal proportional to the weight of said reservoir,

(d) electronic sequencing means operatively associated with said valve means and said weighing means for receiving said output signal for monitoring weight loss from said reservoir as refrigerant is discharged therefrom and for generating signals for controlling said valve means,

(e) adjustable weight differential input means operatively connected to said sequencing means for introducing into said sequencing means a selected value representative of a preselected weight of refrigerant to be discharged from said reservoir,

(f) means for initiating operation of said sequencing means to receive and monitor said weighing means output signal and to provide signals to said control valve means for charging a preselected weight of refrigerant from said refrigerant reservoir into the air-conditioner,

(g) a digital visual display unit for said selected weight differential input means,

(h) wherein said sequencing means senses the weight loss in said reservoir during said charging cycle and said display unit continuously indicates said weight loss,

(i) wherein said sequencing means senses both the weight loss and the rate of weight loss in said reservoir, and

(j) signal means actuated in response to a separate predetermined parameter

of rate of weight loss for said reservoir. .Iaddend. .Iadd.21. A combination as defined in claim 20, wherein said sensing of weight loss by said sequencing means is continuous until said preselected weight of charge is indicated as having been dispensed, and including multiple discreet sensing of said weight loss at timed intervals in response to completion of said continuous sensing, whereby to obtain confirmation of stabilized attainment of said pre-selected weight of charge prior to cessation of the charging cycle. .Iaddend. .Iadd.22. A combination as defined in claim 20, including manually-actuated interrupter means for said micro-processor sequencing means, whereby sequencing can be arrested at any step thereof and restarted from the point of arrest. .Iaddend. .Iadd.23. A combination as defined in claim 20, and further including a high pressure cut-out switch for sensing discharge pressure, said sequencing means generating signals for terminating charging upon sensing of a high pressure by said high pressure cut-out switch. .Iaddend. .Iadd.24. An air-conditioner charging station for charging refrigerant into an air-conditioner comprising:

(a) a reservoir of refrigerant under pressure,

(b) conduit means and electrically operated valve means for selectively connecting or disconnecting said reservoir to the air-conditioner to be serviced,

(c) weighing means for sensing the weight of said reservoir and for substantially continually producing an output signal proportional thereto as weight is decreased during charging,

(d) electronic sequencing means including adjustable refrigerant preselected weight differential input means operatively associated with said valve means and said weighing means for receiving said output signal from said weighing means for monitoring weight loss as refrigerant is discharged from said reservoir into said air-conditioner and for generating signals, including a signal to said valve means for disconnecting said reservoir from the air-conditioner upon receiving a signal indicating that the preselected weight of charge has been dispensed,

(e) means for initiating operation of said sequencing means,

(f) said electronic sequencing means including means for sensing weight loss after the generation of said signal for disconnecting said reservoir at multiple discreet timed intervals and for generating a signal to the said valve means for connecting said reservoir to the air-conditioner upon receiving a signal that a false signal of dispensed weight change was received,

whereby to obtain confirmation of stabilized attainment of said preselected

weight change. .Iaddend. .Iadd.25. A combination as defined in claim 24, wherein said sequencing means senses rate of weight loss in said reservoir, and including signal means actuated in response to a separate, predetermined parameter of rate of weight loss for said reservoir. .Iaddend. .Iadd.26. A combination as defined in claim 24, and further including a high pressure cut-out switch for sensing discharge pressure, said sequencing means generating signals for terminating charging upon sensing of a high pressure by said high pressure cut-out switch. .Iaddend. .Iadd.27. An air-conditioner charging station for charging refrigerant into an air-conditioner comprising:

(a) a powered vacuum pump for evacuation of an air-conditioner,

(b) a reservoir of refrigerant under pressure,

(c) conduit means and electrically operated valve means for selectively connecting or disconnecting said vacuum pump and said reservoir to the air-conditioner to be charged,

(d) weighing means for sensing the weight of said reservoir and for substantially continually producing an output signal proportional thereto as weight is decreased during servicing,

(e) electronic sequencing means operatively associated with said valve means and said weighing means for monitoring weight loss and rate of weight loss as refrigerant is discharged from said reservoir into said air-conditioner,

(f) adjustable weight differential input means operatively connected to said sequencing unit,

(g) means for initiating operation of said sequencing means for sequentially charging a preselected weight of refrigerant from said refrigerant reservoir into the air-conditioner, and

(h) signal means actuated in response to a separate predetermined parameter of rate of weight loss for said reservoir for indicating an inadequate supply of pressurized refrigerant in the charging reservoir or the existence of an inadequate pressure differential between the charging

system and the air-conditioner. .Iaddend. .Iadd.28. A combination as defined in claim 27, and further including a high pressure cut-out switch for sensing discharge pressure, said sequencing means generating signals for terminating charging upon sensing of a high pressure by said high pressure cut-out switch. .Iaddend. .Iadd.29. An air-conditioner charging station for charging refrigerant into an air-conditioner comprising:

(a) a reservoir of refrigerant under pressure,

(b) conduit means and electrically operated valve means for selectively connecting or disconnecting said reservoir to the air-conditioner to be charged,

(c) weighing means for sensing the weight of said reservoir and for substantially continually producing an output signal proportional thereto as weight is decreased during servicing,

(d) electronic sequencing means operatively associated with said valve means and said weighing means for monitoring weight loss and rate of weight loss as refrigerant is discharged from said reservoir into said air-conditioner,

(e) adjustable weight differential input means operatively connected to said sequencing unit,

(f) means for initiating operation of said sequencing means for sequentially charging a preselected weight of refrigerant from said refrigerant reservoir into the air-conditioner, and

(g) signal means actuated in response to a separate predetermined parameter of rate of weight loss for said reservoir for indicating an inadequate supply of pressurized refrigerant in the charging reservoirs or the existence of an inadequate pressure differential between the charging

system and the air-conditioner. .Iaddend. .Iadd.30. A combination as defined in claim 29, and further including a high pressure cut-out switch for sensing discharge pressure, and said sequencing means generating signals for terminating charging upon sensing of a high pressure by said high pressure cut-out switch. .Iaddend.