1990 Sierra Intermittent A/C Heater module

Intermittent A/C Heater with relay clicking. I understand this is a common problem with this module and why GM discontinued it. This module uses the electronic display and electronic board module
combo. Can anyone tell me what particular parts go bad on this board? I would rather replace the components then replace the whole board if possible.
Service # on the module: 16143956 date: 20 Jan 1990 module was a remanufactured unit.
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steven
try this: it worked on mine
good luck
paul
sorry for the caps .. this is the way it is printed
A/C CONTROL HEAD FLASHES/ ERRATIC OPER. OF A/C CONTROLS #46-12-02 - (05/03/1994) 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 BOARDS, POLISH THE TERMINALS ON BOTH SIDES OF THE CAVITY WITH A LEAD PENCIL PINK ERASER. DO NOT USE AN INK ERASER OR OTHER ABRASIVE SUCH AS A SMALL WIRE BRUSH OR SANDPAPER, ETC. DOING SO WILL REMOVE THE TERMINAL COATING AND DEGRADE THE CONTACT SURFACE.
**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 GREASE FROM TUBE AS NEEDED
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