Can someone tell me how the stock A/C systems work and how efficient they are compared to the aftermarket ones available now?

 

I understand R134 is not as effeceint as R12 but the new systems from Classic or Vintage Air work plenty good with R134 to keep the car cool. R12 is getting more and more expensive too. The new systems with R134 are the way to go.

 

Can you be more specific with your question? Do you have an original a/c unit? Are you trying to decide what unit to buy?

As 67 pony said 134 is less efficient. About 15% of the cooling capacity is lost when going from R12 to R134a in the same system. That can EASILY be compensated for by using a 15% larger condensor. So, regardless of whether you use an orignal unit or an aftermarket, you will need more condensor.

If you have a totally original early Mustang unit, the two cylinder compressor does not handle the additional high side pressure of 134, so an upgrade in that area would be warranted.

If you are starting from scratch the ideal unit would be an original underdash unit and then use one of the readily available kits for everything else. This will give you an upgraded compressor and condensor and allow you to have cold air with 134, an original high quality underdash unit and reliability.

If you have a complete original a/c system, simply check it for leaks or any other problems and charge it properly with R12. R12 WAS ridiculously expen$ive, but now that the demand has drastically decreased, it can be purchased for not much more than the cost of R134a.

 

Thanks for the info that was very interesting. But yes I am trying to decide what kind of unit to go with. I don't have any system in my car right now. My car is going to be heavily custom so I'm not worried about if the system is a stock one or not. I would like to use the R134 though since that is what everything is being switched to. Thanks for your info I'll def go aftermarket for the compressor and everything else and maybe do a stock under dash blower unit. Very informative, thanks!

 

waldo,

There was a thread on here a week or two ago that discussed aftermarket a/c choices. It had good information and some good pictures. It would be worth your while to look it up.