Chevrolet Repair: air conditioning, bike tire, conversion kit

Question
what type of refrigerant does a 1999 chevy S-10 pickup require?

Answer
Hi Bob,

Most likely R-134a.  Look at the larger A/C hose and notice the attachment fitting.  Is the cap black?  Is the cap small like a bike tire size?  Is the fitting large?  Looks like a cmpressor air hose fitting or a larger bike tire valve?

The larger compressor air hose looking fitting with the large blue (sometimes black) cap, is R-134a.  

They switched many things about vehicles in 1996.  1996 is the rule of thumb cut-off for older vehicle similarities.  

Look under the hood for a tag that refers to the refrigerant.  

The good side, if it were R-12, it would cost you much to have the system serviced.  You cannot get that refrigerant anymore.  You cannot buy guages and hoses to put it in.  So R-134a is cheaper for you.  And, if by chance you do have R-12, the conversion kit is cheap and easy to do.  R-12 is colder, but the make a R-134a product that makes this refrigerant colder.  

C J S