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AC Compressor

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I have a 1992 Silverado. AC was working normal until I had to swap out the alternator. Shortly thereafter the AC stopped working. The controls are the automatic type. When AC is turned on the AC light flashes and the compressor will not engage. I am hoping this is a minor problem I can handle and would appreciate an imput. Thanks for your help.

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There are two Tech Service Bullintens for your complaints one or both may help you correct you problem.

 

1ST bullinten

Document ID# 250570

--------------------------------------------------------------------------------

HVAC CONTROL HEAD INOPERATIVE NO DISPLAY #93-44-1A - (Oct 22, 1992)

SUBJECT: HEATER VENTILATION AIR CONDITIONING (HVAC) CONTROL HEAD INOPERATIVE - NO DISPLAY

 

MODEL and YEAR: 1990-93 C/K TRUCKS

 

The HVAC control head on some 1990-93 model year C/K trucks may not illuminate when the vehicle is first started. This condition is much more likely to occur after a battery disconnect or control head replacement but may occur after any ignition cycle.

 

The condition is not permanent, it stems from the control head not receiving a correct signal when the ignition is turned on.

 

Recycling the ignition switch may bring the control head back to normal operation. If cycling the ignition does not work, disconnect and reconnect the battery making sure that a good electrical connection is maintained when reconnecting (avoid "chattering" the battery line).

 

-----------------------------------------------------------------------------------------------

2ND bullinten

Document ID# 223984

--------------------------------------------------------------------------------

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.

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There are two Tech Service Bullintens for your complaints one or both may help you correct you problem.

 

1ST bullinten

Document ID# 250570     

--------------------------------------------------------------------------------

HVAC CONTROL HEAD INOPERATIVE NO DISPLAY #93-44-1A - (Oct 22, 1992)

SUBJECT: HEATER VENTILATION AIR CONDITIONING (HVAC) CONTROL HEAD INOPERATIVE - NO DISPLAY

 

MODEL and YEAR: 1990-93 C/K TRUCKS

 

The HVAC control head on some 1990-93 model year C/K trucks may not illuminate when the vehicle is first started. This condition is much more likely to occur after a battery disconnect or control head replacement but may occur after any ignition cycle.

 

The condition is not permanent, it stems from the control head not receiving a correct signal when the ignition is turned on.

 

Recycling the ignition switch may bring the control head back to normal operation. If cycling the ignition does not work, disconnect and reconnect the battery making sure that a good electrical connection is maintained when reconnecting (avoid "chattering" the battery line).

 

-----------------------------------------------------------------------------------------------

2ND bullinten

Document ID# 223984     

--------------------------------------------------------------------------------

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.

 

 

 

 

 

 

 

Thanks for the response. The control head seems to be working OK. The fan works, the heater works, all indicators are normal, except when A/C is turned on. At that point the A/C indicator begins flashing and the compressor will not engage. I have read one other item where this might indicate low freon but was wondering if there might be something more definitive. Thanks

Share this post


Link to post
Share on other sites
There are two Tech Service Bullintens for your complaints one or both may help you correct you problem.

 

1ST bullinten

Document ID# 250570      

--------------------------------------------------------------------------------

HVAC CONTROL HEAD INOPERATIVE NO DISPLAY #93-44-1A - (Oct 22, 1992)

SUBJECT: HEATER VENTILATION AIR CONDITIONING (HVAC) CONTROL HEAD INOPERATIVE - NO DISPLAY

 

MODEL and YEAR: 1990-93 C/K TRUCKS

 

The HVAC control head on some 1990-93 model year C/K trucks may not illuminate when the vehicle is first started. This condition is much more likely to occur after a battery disconnect or control head replacement but may occur after any ignition cycle.

 

The condition is not permanent, it stems from the control head not receiving a correct signal when the ignition is turned on.

 

Recycling the ignition switch may bring the control head back to normal operation. If cycling the ignition does not work, disconnect and reconnect the battery making sure that a good electrical connection is maintained when reconnecting (avoid "chattering" the battery line).

 

-----------------------------------------------------------------------------------------------

2ND bullinten

Document ID# 223984      

--------------------------------------------------------------------------------

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.

 

 

 

 

 

 

 

Thanks for the response. The control head seems to be working OK. The fan works, the heater works, all indicators are normal, except when A/C is turned on. At that point the A/C indicator begins flashing and the compressor will not engage. I have read one other item where this might indicate low freon but was wondering if there might be something more definitive. Thanks

 

 

 

 

 

Actually you should go get a quage and see if you are actually low or not, before doing anything. You can get them pretty cheap from just about any auto parts store.

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