Repair And Fix it

Drive your vehicle to a certified air-conditioning repair shop. Allow a qualified technician to remove all remaining R12 rigerant from your system using a rigerant recovery system. Federal law prohibits the release of this gas into the air.

Instruct the repair shop to flush the system to remove all traces of mineral oil. This will also remove any solid contaminates from the compressor. Mineral oil is not compatible with R134a PAG (polyalkylene glycol) oil, and mixing them could lead to compressor failure. Another option is to use ester oil, which is compatible with both R12 and R134a rigerants.

Return home to complete the conversion. Begin by attaching the new adapters to the old valves. There are two valves: the high-pressure valve is the larger one, and the low-pressure valve is the smaller one. The low-pressure valve is on the line that runs from the accumulator to the compressor, and the high-pressure valve is on the line from the compressor to the condenser. The adapters screw onto the existing ports on the old R12 system, and will attach only one way so you cannot screw them onto the wrong valve. Check the repair manual for a diagram if you are unsure of the location of the valves.

Inspect the valves, hoses and pressure switches for any signs of wear or excessive oil buildup. Replace any parts that leak or show excessive wear so the R134a rigerant will not leak from the same place. R134a has much smaller molecules than R12, so a small R12 leak could be a large R134a leak.

Check your vehicles repair manual for the exact amount of oil to add to the compressor via the low-pressure fitting to lubricate the system. Use the oil and hose included in the conversion kit.

Connect the can of R134a to the hose included in the conversion kit. Turn the T-valve directly on top of the can to puncture it, then very slowly turn it the opposite direction to release a small amount of rigerant from the hose. This removes all air from the hose so it will not be trapped in the system.

Close the T-valve fully and connect the other end of the hose to the low-pressure valve on the line from the accumulator to the compressor. The hose will fit only the low-pressure valve.

Turn on the vehicle and run the air conditioner at the coldest setting. Hold the can of rigerant upright and open the T-valve to allow the rigerant to go into the air-conditioning system. The compressor may not turn on instantly. There is a cutoff switch to prevent damage from low system pressure. Once enough rigerant fills the system, the compressor will engage.

Watch the gauge on the hose connected to the can of R134a to add the appropriate amount of rigerant to the system. Overfilling or underfilling may affect the systems cooling ability. Once the system is full, turn the T-valve completely off and remove the other end from the low-pressure fitting.

Place the plastic caps on the low- and high-pressure fittings and apply the retrofit R134a label in a prominent place to indicate that the vehicle uses R134a rigerant. The caps and label are included in the conversion kit.

Recover any remaining R12 within the air-conditioning system. Use a refrigerant recovery machine to remove the R12 and let the system hold a vacuum for at least five minutes. Repeat the recovery process if the system displays a positive pressure after five minutes. Do not release the R12 into the air, as it is a federal offense to do so.

Flush any remaining R12 mineral oil out of the system. The mineral oil used with R12 is not compatible with the PAG oil used with R134a. Mixing the two oils will result in premature compressor failure. Replace the accumulator or dryer with a unit that contains desiccant that is compatible with R134a.

Inspect the lines, expansion valve, orifice tube and pressure switches for any signs of wear. Replace the components as necessary; otherwise the components may cause the R134a to leak out.

Install a high pressure cut-off switch. Due to the higher pressures associated with R134a, some compressors may need such a switch for increased durability. Install the R134a high side and low side service port fittings and apply the R134a retrofit label that meets SAE requirements in an easily visible location within the engine bay, as required by Section 608 of the Clean Air Act of 1990.

Add the proper amount of R134a PAG lubricating oil into the air-conditioning system. The amount of PAG oil needed depends on the vehicle manufacturers requirements.

Evacuate the air-conditioning system with a deep vacuum pump. This will help remove moisture and excess air from the system. Allow the pump to draw at least 28 in/Hg of vacuum for 10 minutes, then disconnect the pump and allow the system to sit for another 10 minutes. If the system does not lose vacuum, reconnect the pump and finish evacuating the system for another 20 minutes.

With the engine running and air-conditioning system on at its highest fan setting, add the correct amount of R134a to the air-conditioning system. This amount depends on the systems capacity as specified by the vehicle manufacturer. As you add R134a, the compressor will begin to cycle on and off. Do not overcharge the system, as this can damage the compressor and other components. Use a temperature gauge to check the vent temperature inside the car. The temperature should fall at or below 42 degrees Fahrenheit.

Check the air-conditioning system for leaks. Some brands of R134a come with a UV leak detector that is visible under a UV lamp.