How Does a Refrigerant Recovery Machine Work?by Don Bowman
A refrigerant recovery machine became necessary when it was discovered that chlorofluorcarbons (CFCs) were depleting the ozone layer. Once this was discovered, Freon was taken off of the market and maintenance facilities were advised that they needed to have a way of capturing the Freon when extracted. It became illegal to release it into the atmosphere. The recovery machine was quickly developed and certification course was necessary to own and operate one at a shop.
Vehicle Freon Types and Alternatives
R-12, the Freon that was commonly used in cars up to the mid-'90s, was dangerous to the ozone layer. For the above reasons, a new refrigerant that is less harmful to the environment was needed because of the unintentional leaks (such as a blown hose in a vehicle's air conditioning system). A new refrigerant called R-134 was produced. R-134 is far less harmful although still not totally safe. This is the refrigerant that is used in vehicles to date. The race is still on to find something better. All types of liquids have been tested--even propane. So far they all have significant disadvantages--not so much to the environment, but for safety issues or cost factor.
The Problem with Water
Even water could be used to freeze or cool an air conditioning system, but since it needs to be compressed so much in order to bring it to a boil to release enough heat so that when it is reduced to a spray it absorbs the heat of the vehicle. A gas not harmful to the environment is needed that has an exceptionally low boiling point and that is safe around humans.
How a Recovery Machine Works
When a recovery machine is hooked up to the manifold or Schraeder valves on the air conditioning system, it creates a vacuum and sucks all the Freon out of the vehicle, cleanses it through a filter and stores it in a storage tank. When the repair to the system is complete, the machine will vacuum the system down to 30 inches of mercury to rid it of all moisture and air. Freon cannot be inserted into a closed system when there is air present. There is no way to displace air and matter cannot occupy the same space at the same time. After the system is free of air and moisture, the technician will look up the proper amount of charge required for the size system and set the machine to fill the vehicle will the exact charge of Freon. The machine can also detect leaks.