A/C system shutting down on a '94

[k2500]

Hi, new to the forum and have an A/C problem that has been with me for a couple of years on my 1994 chevy. A couple of years ago, my A/C light started blinking on start up and my A/C system would not function. My mechanic went through the trouble codes and found nothing, but did find that after disconnecting the battery the A/C system functioned correctly. Since then I have found that about 2 weeks after resetting, it does the same thing and the A/C stops working. I have also found that if instead of disconnecting the battery, I disconnect the control head at the dash, it has the same effect of resetting things. Any suggestions on where to look for a permanent solution?

Thanks,

Jay

[k2500]

I realized I left out detailed truck info in case it is needed. It is a 4WD, 3/4 ton, auto, 350.

Jay

[bobcat5544]

Document ID# 223984

1994 Chevrolet Chevy K Pickup - 4WD

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A/C CONTROL HEAD FLASHES/ ERRATIC OPER. OF A/C CONTROLS #46-12-02 - (May 3, 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.

[k2500]

Thanks Bobcat, but I did try cleaning the terminals about a year ago with contact cleaner and that did not improve the situation. I'll try the eraser and dielectric grease approach, but if that does not work, is the probable problem the control head?

Thanks,

Jay

[bobcat5544]

It is posible the control head is bad