Leaking Air Conditioner

I have a '97 Sierra and my A/C high pressure port has a slow leak. It's leaking from the port itself with the valve core in it. It's fully tightened but still leaks and leaked out all of my R-134. Can I remove this core and put in a normal tire valve core to replace it? I'll leak off any pressure before taking it out, but will it be a problem just hooking up a can of R-134 once I replace the core?

It would be better to get a AC valve core for it.
Do not hook one of them one hose one can death kits to a high pressure port.

It would be better to get the proper equipment to recharge it.

http://www.ackits.com/merchant.mvc?Screen=PROD&Store_Code=01&Product_Code=66773&Category_Code=RefrigerantGaugeSets

I tried to look up the AC valve core and never came up with a replacement. As far as replacing the R134, I used the can and hose before and never had a problem. I guess my concern is getting ambient air in it while changing the core. Is that a problem or will it be fine to just start putting R134 in immediately? Thanks.

Go to a gm dealer or ac shop.
If system has been leaking you will need to pump it down and do a recharge with the proper amount of freon and proper equipment.

Wal Mart DEATH KITS

You cannot properly and safely recharge an air condition system with them.

The one side stop and go gauge does not tell you what your system is doing or is over charged or undercharged.
A overcharged or malfunction air condition system can reach over 500 lbs of pressure.
Enough to blow up that can or system and freeze you at first and the burn you or blind you and if any propane /butane in there blow and light you up.

The stop leak crap and who knows what kind of oil in the kits there will stop your system for sure.
Just like pouring super glue in it.
And some kits even contain freon with a butane mixer.
Good for a big blast.

If you are going to do it do it right and safe.
Here is what you need to start with.
http://www.ackits.com/merchant2/merchant.mvc?Screen=PROD&Store_Code=AMA&Product_Code=66773

In the older days you could just throw in a can and go.
But over the years just adding freon is getting harder to do.
Newer systems have to have the correct amount of freon down to the ounces.
Most will need pumped down and vacuumed down and the right and amount of oil and a set amount freon charge installed to get the air to cool right and the system to last.
If an air condition is low there is usually a leak that needs fixed and also a lose of lubricating oil from system.
Also air and moisture enters a low system
If you are going to try to do it get the proper type air condition gauge set with the low and high side gauges.
Hook up the gauges and get a reading with compressor running at idle and at 2000 rpm on the high and low side.
Post back pressure reading and we can help you.
MT

I went ahead and replaced the core last night before your post, MT. I had the system tested a year ago and there were no leaks (of course, the valve core still leaked like I told them but that isn't part of their test and they didn't warrant R134). Anyway, the valve core replacement worked and is holding tight. There wasn't much pressure to leak off when I pulled the core and replaced it. Then I put in a can of R134 from an auto parts store and it's blowing cold. I know what you're saying about the pressure though. I'm going to hit the auto shop on my base this wknd to make sure I'm in the green. Thanks for your help.

You are welcome and good luck.
Unless the can was a big one you may need some more.
MT