What can happen when you air conditioner gets charged with the wrong Freon?
Short answer: you will get this mixture of GOO, in your system, that will burn up your compressor in a very short time. Therefore R12 and r134 cannot be mixed… they are incompatible and don’t work as a mixture.
Being a 1993 the air conditioning system originally required R-12 Freon. If at anytime it was converted to R-134a Freon, the installation ports would have been changed to only accept the newer style Freon. This makes it difficult to add the wrong type of Freon.
If for some unforeseen reason the two were intermixed, the entire system will need to be flushed. The orifice tube, o-rings and accumulator will need to be replaced as well. And if the system was operated with the contaminated Freon, you may also need to replace the Compressor.