Materials
- R-134a refrigerant (you will need to determine how much based on your vehicle's specifications)
- PAG oil (also known as polyalkylene glycol oil)
- O-rings
- Schrader valves
- Refrigerant hose adapter fittings (these will allow you to connect the R-12 fittings to the R-134a fittings)
- A/C manifold gauge set
- Vacuum pump
- Safety glasses
- Gloves
- Wrench set
- Screwdriver set
- Recovery tank
Steps
1. Recover the R-12 refrigerant. Use the manifold gauge set to attach a recovery tank to the low-pressure port of the A/C system and turn on the recovery machine.
* You must wear gloves and safety goggles when handling refrigerant.
* Open the low pressure valve on the manifold
* Ensure that the recovery tank has enough capacity.
2. Pressurize the system with nitrogen. Once you have recovered all the R-12 refrigerant, pressurize the A/C system with nitrogen.
* Open the high side valve, disconnect recovery and connect the nitrogen cylinder.
* Apply 20 psi to 30 psi of nitrogen pressure.
* Allow the nitrogen to sit in the system for at least 15 minutes.
3. Release the nitrogen. Once you have pressurized the system with nitrogen, release the nitrogen by opening the low pressure valve on the manifold.
4. Replace the Schrader valves. While the nitrogen is releasing replace the Schrader valves with new ones specifically for R134a.
5. Replace the O-rings. Replace all of the O-rings in the A/C system.
6. Add the PAG oil. Add the specified amount of PAG oil to the A/C system. This is important for lubricating the compressor.
7. Add refrigerant. Add the specified amount of R-134a refrigerant to the A/C system. You will need to use an adapter fitting to connect the R-12 fill port to the R-134a refrigerant can.
8. Start the engine and test the A/C system. Start the engine and turn on the A/C system. Check the A/C system for leaks and make sure that it is cooling properly.
* This is a complex process that should not be attempted by someone without experience working on automotive air conditioning systems.
