with a machine you recover the coolant that's in the system and then vacuum to boil out any moisture, then charge to an exact amount.
that way you know how much is in the system because too much is just as bad as not enough. If there's some in there you don't know how much to add to get the correct amount.
the 2003 VIII capacity is 18 oz. of R134. (there should be a sticker under the hood somewhere)
With cans you might be able to drain everything out that's in there by pushing down the schrader valve. And then add the correct amount.
Look the system over for oil leaks, like a big dirty patch on the condenser, if there's big oil leaks or if there's very little or no pressure when you push the schrader you have a big leak that should be fixed first before adding R134.
the system contains oil to lube the compressor. It leaks out when you have a big r134 leak. If a large amount leaks out or if you change a component you need to add some oil .
Last edited by NWM_Tech; Aug 8, 2009 at 08:44 AM.