a/c's not working...HELP?

i have a 91 chevy 1500 and my a/c light is blinking. i know that this means that it doesent have freeon, but mine is fully charged and has no leaks. i pulled a vacuum on it to make sure. i can unplug my control panel unit and plug it back in and it will work for a minute or two (and run really cold). then the a/c light will blink again. and i dont know what the problem is now... HELP?!

Heating and Air Conditioning: By Symptom A/C Control Head - Flashes, Operates Erratically Group Ref.: HVAC Bulletin No.: 461202 Date: May, 1994 SUBJECT: A/C CONTROL HEAD FLASHES OR ERRATIC OPERATION OF A/C CONTROLS (POLISH TERMINALS) MODELS: 1988-94 CHEVROLET AND GMC TRUCK C/K MODELS 1990-94 CHEVROLET AND GMC TRUCK TOPKICK/KODIAK MODELS WITH C60 OR C69 AIR CONDITIONING CONDITION: A/C Control Head flashes, performs erratically or malfunctions. CAUSE: Light surface corrosion on the Control Head terminals. CORRECTION: Remove the A/C Control Head and while holding the unit with the terminal cavity down (toward the floor) so no particles will fall inside on the circuit Performing this procedure, in many cases, will make replacing the Control Head unnecessary. Using this procedure in conjunction with the A/C circuit diagnosis found in the Electrical Diagnosis Manual and especially before replacing a Control Head for any reason is recommended. After polishing the Control Head terminals, but before reconnecting, check for proper terminal contact as described in the applicable electrical diagnosis manual. If contact is good, apply dielectric grease (P/N 12345579) to the harness connector terminals. Please do not apply grease to the Control Head. SERVICE PARTS INFORMATION: P/N Description QTY 12345579 Dielectric From Tube as Grease Needed Parts are currently available from GMSPO. WARRANTY INFORMATION: For vehicles repaired under warranty, use: Labor Description Labor Time Operation D0362 A/C CONTROL Use Published ASSEMBLY Labor Operation Replace Time