Holding Plates- cleaning out r12 to replace with R134a

[Kapejna]

Hi,
can anyone advise what can be used to clean out a holding plate that may have a residue of R12 mineral oil so it can be made safe for use in an R134a system? The R12 oil and R134a compressor oils are incompatable, and I believe from reading Richard Kollmann's refrigeration book a small amount of mineral oil can have very bad effects on a R134a system. Can anyone who has gone thru this process offer advice?

Thanks

tony
one24c@aol.com

[easterly]

Here the info from AC Delco. Only flush refrigeration system with refrigerant. If you flush with solvent and leave any solvent in the system you will ruin the compressor. You can leave the R12 mineral oil in the system if you use PAG oil. Do not use ester oils. They break down and the compressor will fail. My cold plate uses R22. You can mix R22 and R134a.

[Richard Kollmann]

Tony, there are boat refrigeration systems that can easily be converted from R12 to 134a without removing all of the mineral oil. Not knowing what type system you have and who manufactured it I can not comment on your system.

Easterly, You are offering bad information. You can not mix refrigerants. Polyester (POE) conversion oil is safe in many engine driven conversion system. PAG oils are not recommended by any boat refrigeration manufacture I know of and some PAG oils can destroy internal materials inside a system.