AC recharge

the ac isn't that cold, so I went to recharge our 98 Yukon. But, I see what look like the two ports, but I don't know which one is the low pressure port, can anyone help?

Second, I was going to use the gauge and hose I've used to recharge my other cars (Volvo), but, the hose connector is too small for to fit over what I think is the port, is there a larger connector used for GMC's?

thanks again!

You should have a red and blue cap on those ports. If the port is large it is R-1345. I don't know if ytou have R-134 or R-12, but you shoulkd have 134. If you are in doubt - take it in. You don't want a can of freon exploding in your face!

A 98 is R134a.

//2000CAYukon

You should have a red and blue cap on those ports. If the port is large it is R-1345. I don't know if ytou have R-134 or R-12, but you shoulkd have 134. If you are in doubt - take it in. You don't want a can of freon exploding in your face!

The only 2 ports I see both have black caps on them, and they are too large for hose fitting, so I'm guessing that they aren't what I'm looking for.
Where is the location of the ports you are talking about?
Thanks again

The AC valve is near the back firewall on the left side (facing the windshield from the grill) of the engine. It is behind the near the alternator behind the coils. You have to "squeeze" your hand back there. I have one of thiose AC atachments that you Slide up, clip on and let it slide loose to connect.