A/C LIGHT BLINKS IN HVAC CONTROL??

[redchevy914x4]

I have a 91 K1500 with the electronic HVAC controls. When I start the truck or simply turn the key on, the A/C light in the controls blinks for a while then just stops. It doesn't seem like it really affects anything other than the light blinking. It has done it for a while but since the truck is not my daily driver, I haven't really worried about it. I am just curious about it now. Have any of you had a similar problem and if so, what did it end up being?

 

[RHamill]

Is the AC button pushed? If so it's probably a bad connection on the bulb behind it, and the idling of the truck or subtle movements makes it lose connection for a second.

 

[redchevy914x4]

No, the A/C button isnt pushed. Is there a way to take the hvac control apart to check the connection on the bulb? It does it all the time when I turn the key on, it doesn't matter if the truck is actually running or not.

 

[SinisterSilverado]

I was reading my user manual the other day and it mentioned if the a/c button blinked like that it meant you were low on freon. Might be that.

 

[///RAGMC]

I was reading my user manual the other day and it mentioned if the a/c button blinked like that it meant you were low on freon. Might be that.

This is true. There is also a service bulletin that tells you how to override it

 

[redchevy914x4]

This is true. There is also a service bulletin that tells you how to override it

Any idea where I can find this service bulletin?

 

[///RAGMC]

Any idea where I can find this service bulletin?

Ill try and see if I can find it or maybe some one will chime in

 

[DRAGGIN95]

You must be registered for see images

You must be registered for see images

You must be registered for see images

Conversion Calculator

You must be registered for see images

1991 Chevy Truck C 1500 Truck 2WD V8-350 5.7L


Vehicle Level

You must be registered for see images

Heating and Air Conditioning

You must be registered for see images

Technical Service Bulletins

You must be registered for see images

All Technical Service Bulletins

You must be registered for see images

A/C - Low Charge Indicator Flashes in Error

You must be registered for see images

You must be registered for see images

A/C - Low Charge Indicator Flashes in Error
9232chevy02
Number:92-201-1B
Section:1B
Date:MAY 1992
Corporate Bulletin No.: 261201
ASE No.: A7
Subject:
AIR CONDITIONING LOW CHARGE
INDICATOR FLASHES
Model and Year:
1991-92C/K TRUCKS
Some owners of 1991-1992 C/K vehicles may comment that the A/C letters in the middle of the control head face are flashing. The HVAC control system used on 1991 and 1992 C/K vehicles incorporates a low A/C charge warning system. If a low charge is detected, the control head will not allow the compressor to engage and the A/C letters in the middle of the control head face that usually signify A/C operation will blink.
The HVAC control head determines a low charge by monitoring the circuit from the pressure cycling switch. If the cycling switch will not allow the compressor to run more than 1.5 seconds, ten times in a row, the control head assumes a low charge and disables the compressor until reset.
On some vehicles, it has been found that the wire from the pressure cycling switch to the control head is sensitive to EMI (electro magnetic interference) and gives false compressor cycling information to the HVAC control head which then disables the compressor.
If you encounter a vehicle with the control head A/C indicator flashing the low charge signal, but can find no reason for the flash using normal diagnostic procedures; including checking the wiring harness for chafing; remove the pressure cycling switch feedback wire from the control head connector using the service procedure outlined below. This process disables the A/C Low Charge detection feature, however, the customer will still be alerted to a low charge by excessive compressor cycling and poor A/C performance.
SERVICE PROCEDURE
1.Remove the instrument panel trim bezel.
2.Remove the A/C control head.
3.Disconnect the control head electrical connector.

You must be registered for see images

4.Remove the dark green circuit 59 wire located in harness connector socket number one. Do not cut the wire, remove the terminal (Figure 1).
5.Fold the wire back along the harness and tape it so that it cannot short when the control head is installed.
6.Install the control head.
7.Install the instrument panel bezel.
WARRANTY INFORMATION
For vehicles repaired under warranty use:
Labor Operation0362
Use applicable labor time guide for labor hours.

You must be registered for see images

© 2011 ALLDATA LLC. All rights reserved.Terms of Use

 

[///RAGMC]

You must be registered for see images

You must be registered for see images

You must be registered for see images

Conversion Calculator

You must be registered for see images

1991 Chevy Truck C 1500 Truck 2WD V8-350 5.7L


Vehicle Level

You must be registered for see images

Heating and Air Conditioning

You must be registered for see images

Technical Service Bulletins

You must be registered for see images

All Technical Service Bulletins

You must be registered for see images

A/C - Low Charge Indicator Flashes in Error

You must be registered for see images

You must be registered for see images

A/C - Low Charge Indicator Flashes in Error
9232chevy02
Number:92-201-1B
Section:1B
Date:MAY 1992
Corporate Bulletin No.: 261201
ASE No.: A7
Subject:
AIR CONDITIONING LOW CHARGE
INDICATOR FLASHES
Model and Year:
1991-92C/K TRUCKS
Some owners of 1991-1992 C/K vehicles may comment that the A/C letters in the middle of the control head face are flashing. The HVAC control system used on 1991 and 1992 C/K vehicles incorporates a low A/C charge warning system. If a low charge is detected, the control head will not allow the compressor to engage and the A/C letters in the middle of the control head face that usually signify A/C operation will blink.
The HVAC control head determines a low charge by monitoring the circuit from the pressure cycling switch. If the cycling switch will not allow the compressor to run more than 1.5 seconds, ten times in a row, the control head assumes a low charge and disables the compressor until reset.
On some vehicles, it has been found that the wire from the pressure cycling switch to the control head is sensitive to EMI (electro magnetic interference) and gives false compressor cycling information to the HVAC control head which then disables the compressor.
If you encounter a vehicle with the control head A/C indicator flashing the low charge signal, but can find no reason for the flash using normal diagnostic procedures; including checking the wiring harness for chafing; remove the pressure cycling switch feedback wire from the control head connector using the service procedure outlined below. This process disables the A/C Low Charge detection feature, however, the customer will still be alerted to a low charge by excessive compressor cycling and poor A/C performance.
SERVICE PROCEDURE
1.Remove the instrument panel trim bezel.
2.Remove the A/C control head.
3.Disconnect the control head electrical connector.

You must be registered for see images

4.Remove the dark green circuit 59 wire located in harness connector socket number one. Do not cut the wire, remove the terminal (Figure 1).
5.Fold the wire back along the harness and tape it so that it cannot short when the control head is installed.
6.Install the control head.
7.Install the instrument panel bezel.
WARRANTY INFORMATION
For vehicles repaired under warranty use:
Labor Operation0362
Use applicable labor time guide for labor hours.

You must be registered for see images

© 2011 ALLDATA LLC. All rights reserved.Terms of Use

Yep thats it thanks for finding it

 

[DRAGGIN95]

Glad to help!