What kind of freon goes in my 90 5.0 for the ac?

 

From the factory, R12 came in it. If you don't want to run R12, it will need to be converted to R134a.

 

Thank you!

But what's the difference?

 

Well, R12 was phased out after '93 due to environmental concerns. It is still available, but it is VERY expensive and IIRC, you now need a license to buy it. In my opinion, it cools much better than R134a, but a well thought out and executed R134a system can still blow ice cold air.

R134a is what has came standard in vehicles made from '94 up and is readily available pretty much anywhere. You can retrofit your system to work with R134a and make it work well, but you have to be spot on with having a clean (or thoroughly flushed) system, the correct viscosity PAG oil, the correct amount of PAG oil and the correct amount of R134a for your system to blow ice cold air. With R12, it wasn't as "picky" about everything being so exact to blow ice cold from my experience with it. R12 was truly a wonder from the good ol days lol.