Is it easy to convert a classic unit to the new type of freon. I have a guy that is selling he factory under dash unit to me for $500. it is complete and working right now in his car.

 

I have "converted" lots of cars from R12 to R134. Some work great others don't. The problem is with the condenser in the front of the radiator. R134 doesn't dissipate heat as well as R12 so you need a larger/different style condenser. I am running a condenser from a 2000 Lexus GS and it fits perfectly on my 68 coup. All my lines are custom so you are on your own as far as how to hook it up but its the best fit for a R134 condenser I have found.

You should just try it stock first and see how it works, it could be OK. Usually if the condenser is too small it will still cool at highway speeds but not sitting still.

 

well i have opend up the front end of my 66 and installed a aluminum radiator and a 6 blade flexlight fan. When i opened it up i cut out about 4"s of sheet metal out of both sides of the core support. Will that help.

 

I have a refurbished original underdash unit with a Sanden compressor and 134a. I changed the expansion valve on the original unit. You'll need barrier type hoses and maybe a new condensor and dryer. I got every done from Classic Auto Air. Acutally having your radiator support opened up could hurt how well the AC functions. It needs the sides closed in around it so air moves through it.

 

tx65coupe makes a good point about the air flow. Air will take the path of least resistance, it will go around the radiator/condenser rather than through it.

he is also right about the barrier hoses. Get Galaxy hose made by GoodYear.
you can try it out with the original hose to see if it will work but it wont last longer than one summer.