Can someone tell me where is low port

[vikasintl]

Please check pic. attached from 1989 gmc s15 and I cant figure out which one is low port ?

[BlackZ71Silverado]

Are you trying to recharge the A/C?

I noticed your other post where you said you had already added 134a. The valve that comes on those do it yourself A/C charging kits will ONLY fit the low service port, the others are too large. It's going to be the one with the gray cap on it, on the left side.

 

The low service port will always be the smaller of the valves.