Heater a/c control light stuck on.

[duke10]

I have a 72 GMC Sierra Grande and my heater control light is stuck on illuminating the right side where it says defroster De ice Heater and Hot.
Any ideas on how to get it turned off?
Thanks in advance for any help

[Sheepdip]

Those come on with your dash lamps. I believe somethings got a hot 12 volts to it when it shouldn't have.

[duke10]

I was just dealing with a horn wiring issue, I wonder if that could
be the issue.

[RustyPile]

Originally Posted by duke10

I was just dealing with a horn wiring issue, I wonder if that could be the issue.

Probably not, dash lights and horn circuits are 2 totally different circuits.. The grey wire at the fuse box carries voltage from the headlight switch to the cluster plug.. A second grey wire at that cluster plug is "piggybacked" with the one from the fuse box.. That wire goes to the light in the heater control.. The bulb wire in the heater control has become disconnected from the cluster plug and then "shorted" to some always hot circuit/wire.. If it was still connected, all the gauge illumination bulbs would be lit.. Trace that grey wire at the heater control, you'll find the problem...

{EDIT} If you don't have a wiring diagram, get one.. It's the number tool when doing electrical work.. Go to the ELECTRICAL forum and download the one for your truck...