Conversion of an Air Conditioning System to R134a Refrigerant

Rattlesnake Mountain Enterprises has had several customer ask about converting pre-R134a to R134a refrigerant in their older cars. The classic question is “I bought this $59.95 kit at the local discount store and it says that it is easy to convert my system, Is it easy and will it work for very long?” This is really a trick question and the customer usually knows the answer or he or she would not ask.

Yes you can convert nearly any mobile air conditioning system to R134a. The trick part is do you want it to last or not. Proper conversion of an air conditioning system requires some skill and specialized equipment. With out the proper equipment you will violate several environmental protection laws.

We have tried both the simple conversion and the complete retrofit of the air conditioning system to use R134a. The simple method is to remove the old refrigerant, add new oil that is supposed to be compatible with just about all refrigerants. The fittings are changed by adding adapters and the system is recharged with one pound cans of refrigerant. Please remember that you must add the correct service port fitting for R134a. Current law requires that each type of refrigerant installed in a car now have a unique service port fitting used only for that special type of refrigerant. This is basically the simple conversion as described in the kit. There are a number of problems with this process.

• ● What are you going to do with the old refrigerant is it is something other than R12 or R12 mixed with something else? It is costly to dispose of this refrigerant and illegal to vent it to the atmosphere. Your solution is to have a properly equip ed shop recover the old refrigerant. If it is a mixed refrigerant it might cost you some bucks, be prepared.
• ● If your system has had stop leak added to it you many not be able to find a shop the recover the refrigerant or to retrofit the system.
• ● Even after you have the system recovered it should be evacuated for 15 minutes to one hour depending on the temperature.
• ● How are you going to know when you have added the correct amount of refrigerant?
• ● Your compressor may not last more than a few months due to lubrication problems cause by the mixed lubricating oils. If you don't extract as much oil as possible from the compressor you are almost certain to have problems.

The second method is to do a quality retrofit of the system. If this is done it will provide good service for an extended period of time. Things that a quality retrofit includes:

• ● Identify and recover the refrigerant.
• ● Remove all connections and replace o-rings.
• ● Flush evaporator and condenser.
• ● Replace orifice tube or the expansion valve.
• ● Replace either the receiver drier or the accumulator drier depending on the condition.
• ● Install correct service port adapters.
• ● Evacuate the system for 30 minutes.
• ● Charge the system.
• ● Test system for efficiency.
• ● Check system for leaks.
• ● Attach correct labels.
• If the system checks out return the vehicle to the customer, if not get an authorization to repair the bad component of the system. If the system came to the shop inoperative and what one does not, do diagnostics that you can with out charging the system before conversion. The cost of a proper refit of a system will run $400 to $600. If there are many failed components the bill will be higher.

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