I have recently become aware of the epidemic practice of 'topping off' HCFC-22 air conditioning systems with other refrigerants, particularly R-422D by service personnel in central Florida. (Yes, I know 422D is for low and medium temp, but the jug IS somewhat green)
For the most part, the personnel I have personally conversed with contend that this practice is condoned, if not mandated, by their employers.
Talking to supply house personnel further exposes that this practice is widespread in this area, and I suspect it may be strongly prevalent across Florida and nationally. Many posts here tend to uphold this conjecture.
I am approaching my 40th year in the industry, and find the lack of professionalism revealed by this to be utterly indefensible.
I queried RSES and got this reply: "The answer is YES. By topping off with a different refrigerant the tech is creating a non-EPA SNAP approved refrigerant. I'm not sure where to locate the specific regulation but this info is correct from my discussions with EPA officials."
In our school district all systems that can be drained or vacuumed of their MO, are being retrofitted to R-407C and POE at the time they are being serviced for leaking refrigerant charges.
Our results have been above our expectations; the systems exhibited exemplary cooling performance and energy consumption characteristics; we have found that in our MO units that can not be easily relieved of the MO charge, MO oil return with R-407C is successfully enhanced with the addition of Supco 88 to thin the MO, in place of the hydrocarbon content in 438A, 422D, etc.
DuPont has acknowledged that the basic reason for the hydrocarbon content in these blends is to thin the MO in an effort to provide a bit of oil return; the more hydrocarbon in the blend, the better thinning of the MO.
We've had first-rate oil return results by adding Supco 88 as an alternative to the hydrocarbon content of the 'no-oil-change' refrigerants; probably due to Supco being 98%-99% hydrocarbons.