A/C Needs Refrigerant

I seem to have a small leak in my 92 VR-4. The previous owner replaced the R12 with R134.

I purchased a can of R134 at the local parts store and the instructions indicate that I should add it to the low-side Schrader valve.

Where can I find this valve on the 92 VR-4?

Thanks

You need some pressure gauges... its a complete setup with hoses and gauges to tell how much refrigerant you have in the system, and for other things. i recommend you just take it to a shop and let them do it. The good thing about R134 is it is less toxic than R12, and also cheaper. Way to go on the R134 switch.