Where is the low pressure valve on a 1998 Astro to add a 134r charge kit?

On a 1998 Chevy Astro, the low-pressure valve for adding R134a refrigerant is typically located on the larger diameter aluminum line that runs between the evaporator and the compressor. It is usually found near the front of the engine compartment, close to the passenger side. The valve is typically capped with a plastic cover, which you will need to remove to attach your charging kit. Always ensure the engine is off and the AC is set to the max cool setting before adding refrigerant.