A/C Confusion. Please help.

[synfrag69]

91 240SX SE - KA24DE

Now that it's summer and so far a hot one in Denver My A/C hasn't been running very cool. So like any other cheapskate these days I went down to Advance and bought a recharge set. I've done recharges on other cars in the past with smashing success. So I popped my hood and didn't notice any blue caps anywhere on the AC lines. I know that the Low pressure is the side to fill on so looking down from the drivers side around the dipstick area I was able to find a black capped port. But, this port does not have a quick connect nipple on it but rather a short threaded valve very similar to the high port. The recharge kit will certainly not fit this. Is there a quick connect nipple that should be threaded onto this? I've searched all over for diagrams and pictures and none match mine and the FSM is a bit cryptic on the AC system. I'll try to throw some pics up when it's light out. Any suggestions other than take it to a shop which i will do if I can't get some advice on it.

Thanks!
Charles

[sx moneypit]

Your car has an R12 (freon) system.You are going to have to retrofit the system to accept R134 or take it to a shop to have it filled with R12.You cannot buy R12 unless you are certified in AC.

[dmck]

r12 is very expensive anymore advance sells a retrofit it is very easy to install it on the r12 system it is only like 10 dollers

[mdm89]

you will still have to take it to a shop so you can get the system evacuated. you dont really want to mix coolants

[synfrag69]

Ok thanks for the confirmation. I figured it was an R12 system. For some reason I thought I had recharged it once before but it must have been my last car.