Minimum requirements for converting a system to R134a.

[Tim]

Minimum requirements for converting a system to R134a.

If the system has any refrigerant R12 left, reclaim with an approved recovery machine.

The accumulator/drier must be replaced with an R134a compatible replacement. R134a conversion fittings and labels should be added. The label should list the amount of R134a used and the quantity and oil type listed. If the vehicle is not equipped with a high-pressure cut-off switch, it should be added.

That is the required minimum!

Additional steps.
Flushing system removing the mineral oil and debris should also be done. O-rings should be replaced with either NBR or HNBR replacements. Adjustment of the pressure cycling switch may also be needed to achieve the best performance. In some cases, an upgrade of the condenser may be required to achieve the original performance. Not all manufacturers offer a drop-in Parallel flow replacement condenser. Universal PF condenser will work with custom hose lines

There are many different suggestions when charging an R12 system with R134a. The A/Csystem should be evacuated before starting the charging procedure. I suggest you start with about 80 percent of the original R12 charge and add an ounce at a time until vent and pressure readings reach the best available results. Remember, it is easy to overcharge a system with R134a, so patience is essential.