1993GMCSierra
I'm Awesome
Also, unless it's been converted (it will have a sticker either on the silver canister by the firewall, or on the compressor or radiator support saying "This vehicle has been converted to R134a" ), you're likely still driving with R-12 in the system. R12 was used up until the 1994 model year.
If it is, you cannot simply go to a store, buy a can of R-12 and "top it off". R-12 hasn't been sold since 1996, and these trucks do not convert to R-134a that well.
Your best bet is to get some R-12 manifold gauges off eBay, and a R-12 can adapter, and a can or two of R-12.
Check the pressures to see where you're at, the low side should stay around 28-32 with the A/C on MAX, and the idle around 1500. I would add freon until it's around there.
Is the air still cold? Do you have a thermometer to stick in the vents to see how cold?
If it is, you cannot simply go to a store, buy a can of R-12 and "top it off". R-12 hasn't been sold since 1996, and these trucks do not convert to R-134a that well.
Your best bet is to get some R-12 manifold gauges off eBay, and a R-12 can adapter, and a can or two of R-12.
Check the pressures to see where you're at, the low side should stay around 28-32 with the A/C on MAX, and the idle around 1500. I would add freon until it's around there.
Is the air still cold? Do you have a thermometer to stick in the vents to see how cold?