Preparation

• 1). Get a vacuum pump. A strong pump can be economical, since the cost of a professional service will exceed the cost of the tools. Also, if your conversion fails to work perfectly, you can always do it again.
  
  
• 2). Buy a conversion kit. Some are made for GM brands, while others are universal and apply to all vehicles.
  
  
• 3). Replace the filter/drier. Make sure your conversion kit includes one that is R22 compatible.
  
  
• 4). Remove the existing expansion valve.
  
  

Installation

• 1). Remove the existing drier, disconnecting the lines at the compressor.
  
  
• 2). Pour isopropyl alcohol into the lines ones at a time. Blow air through the lines afterwards using the blowgun. This pushes the contents out of the line at the compressor end. Use a bucket to catch the contents.
  
  
• 3). Install the new drier and expansion after flushing both the condenser and evaporator sides of the air conditioner.
  
  
• 4). Investigate for leaks using a UV light, checking the entire system including the condenser for any traces of UV dye. Clean any stains with isopropyl alcohol.
  
  
• 5). Hook up the manifold set, and attach the a vacuum to the system. Once a vacuum is established in the manifold for 15 minutes, shut the gauges, close the ball valve and turn off the pump. Let everything sit for 15 minutes. Open the manifold valve and check if the vacuum has held. Close the manifold gauge and let it sit another 45 minutes, and repeat the 15 minute wait. If the vacuum is maintained on both occasions, it's a good assurance there are no leaks.
  
  
• 6). Inject the oil in the injector tool, and inject one can of R22 into the system, Disconnect the injector, reconnect the hose and put in two additional cans of R22. If more than three cans are required, insert the remainder that is necessary.