'90 6000 LE, 3.1Ltr. Are you still able to go to your local auto store...{mine is advance auto} and pick up some freon and fill your air conditioner yourself or do I need to take it in and get ripped off. Thanks.

You car is prolly R12 so you would need a conversion kit. If you have the money to do it right get the system evacuated and pressure tested by a licensed AC tech first so you are not wasting your time and money on new freon.