I have a 1992 GMC K1500 and the A/C light blinks in the HVAC controls. The compressor is about 5-7 years old, new lines, new orings, new hi pressure sensor and fully charged. If the battery is disconnected and reconnected the compressor clutch will kick on and off repeatedly until the light starts to blink. I've tried different controls from a scrapyard, but to no avail, any ideas?