How many cans of freon for a 85 Chevy S10?

There's no single answer to how many cans of freon (R-12 or R134a, depending on whether the system has been converted) are needed for an 85 Chevy S10 AC system. The amount depends on the size of your system and any leaks that may exist.

Instead of trying to guess the amount, you should:

* Have a qualified technician service your AC system. They'll properly diagnose any leaks, evacuate the old refrigerant, and recharge the system with the correct amount of refrigerant (R-134a if it's been converted, or R-12 if it hasn't and you can legally source it – R-12 is largely phased out). Using the wrong amount or type of refrigerant can damage your system.

* Don't attempt to recharge the system yourself without proper training and equipment. Refrigerant handling requires special tools and safety precautions to avoid injury and environmental damage.

Trying to guess the amount based on cans is inefficient, risky, and likely to result in an improperly functioning or damaged AC system. Professional service is the safest and most effective method.