text: The present invention relates generally to the handling of refrigerant and, in a preferred embodiment thereof, more particularly relates to apparatus and associated methods used in refrigerant recovery, recycling and flushing operations carried out in conjunction with air conditioning refrigerant circuits.
  The refrigerant repeatedly cycled through a typical air conditioning circuit--normally consisting of a compressor, condenser, expansion valve and evaporator connected in series--is subject to contamination from a variety of causes requiring that the contaminated refrigerant be cleansed or replaced. For example, a burnout of the circuit's compressor motor typically contaminates the circuit refrigerant with acid, moisture, and a variety of "trash" such as valve reeds, piston rings and metal shavings - all of which would be highly detrimental to the new compressor motor subsequently installed if not appropriately removed from the air conditioning circuit.
  For many years, the conventional approach to handling contaminated refrigerant was simply to vent it to atmosphere, flush out the circuit using high pressure compressed air, and then recharge the circuit with new refrigerant prior to the installation and operation of the new compressor motor. This long-used technique, however, wastes expensive refrigerant. It is also now known to be deleterious to the environment. Because of this, the prior practice of simply dumping contaminated refrigerant to atmosphere is, to a rapidly increasing extent, being proscribed by applicable environmental regulations.
  In response to the growing awareness of cost and environmental protection, various "closed loop" methods of handling contaminated refrigerant have been proposed to prevent refrigerant discharge to atmosphere. There are now basically three types of closed loop processes used to deal with the problems of contaminated refrigerant in an air conditioning circuit--recovery, recycling and flushing.
  The closed loop refrigerant recovery process entails simply drawing the contaminated refrigerant through appropriate piping or hoses into a closed receiving vessel which may later be moved to a processing location where the contaminated refrigerant in the vessel may be cleanses and re-used. The recycling process involves the circulation of the contaminated refrigerant through a recycling circuit externally connected to the air conditioning circuit and functioning to cleanse the refrigerant of impurities therein, such as acid and moisture, so that the cleansed refrigerant can be directly re-used in the air conditioning circuit. The flushing process is conventionally carried out by forcing clean refrigerant through the previously emptied air conditioning circuit and then, through a closed loop path, into a suitable receiving vessel for subsequent cleansing and recycling.
  Various closed loop combination refrigerant recovery/recycling machines have been conventionally utilized to perform both the recovery and recycling processes described above. Additionally, a recovery/recycling machine having a refrigerant flush mode uniquely incorporated therein is illustrated and described in the aforementioned copending U.S. application Ser. No. 07/968,199.
  Though quite useful in providing their refrigerant handling functions in a closed loop fashion so as to eliminate harmful refrigerant discharge to atmosphere, these machines are typically characterized by a large size and weight (usually weighing on the order of 300 pounds) and are relatively expensive and complex. Additionally, at least the conventionally constructed machines tend to have relatively slow recovery and recycling rates since they handle the refrigerant being recovered and/or recycled in a gaseous phase.
  The sheer size and weight of previously utilized refrigerant recovery/recycling machines has tended to make them relatively difficult to use in a variety of commonly encountered limited access situations. For example, when the compressor burns out on a roof-mounted air conditioning unit it is difficult, if not impossible, to use a conventional closed loop refrigerant handling machine to recover or recycle the contaminated refrigerant in the air conditioning circuit since the moving of a 300 or so pound machine up to the rooftop presents at best a rather formidable task.
  It can be seen from the foregoing that is would be desirable to provide improved closed loop refrigerant handling apparatus and methods that eliminate, or at least significantly reduce, the above-mentioned problems, limitations and disadvantages of the refrigerant handling equipment generally described above. It is accordingly an object of the present invention to provide such improved apparatus and methods.