I have a 99 ford xlt explorer and want to recharg my A/C how do I know if its a r134a system or a R12? (owners manual didn't say squat)

Your truck should use R134a. It should be listed under the hood.

There should be an EPA sticker next to the hood latch. There should be something in the fine print.
Irregardless you have a R134a system. R12 went away in 1993.

thanks and sorry for the double posting wasnt really sure where to put the question - new here.

Thanks.

Welcome to the forum. Lots of good info here. Take your time and look around and you will be amazed at what Explorer info is there to be found.
By the way, double posting means you owe us all a beer.

Ok checked the label and sure enought its r134a as mentioned above - thanks. Now after reading my recharge kit instructions it says to connect the guage and hose to the recharge can and my low pressure port. I see two ports up by the radiator one with a black cap and one with a green cap, how do I know which one is the low pressure port? (The instructions said if i use the high pressure port the can will explode :eek: )

The fitting will only fit on the low side port. The high pressure one has a larger fitting.

thanks - didnt get that far... :confused:

Ok checked the label and sure enought its r134a as mentioned above - thanks. Now after reading my recharge kit instructions it says to connect the guage and hose to the recharge can and my low pressure port. I see two ports up by the radiator one with a black cap and one with a green cap, how do I know which one is the low pressure port? (The instructions said if i use the high pressure port the can will explode :eek: )

The low pressure port is near the passenger side fire wall... The port with the green cap is for emissions testing not for the AC...