2004 Chevy Tahoe: Car's horn went off on its own, and wouldn't stop until I pulled the fuse. This was a continuous sound of the horn. Not short honks. Vehicle was parked in my garage and the engine was off. Initially, I tried to use my key-fob's lock/unlock and panic feature, but that did nothing to stop the horn. I also started, and then turned off the engine, but that also failed to quiet the horn. When I went to put the fuse back in in the morning the horn went off again. I left the fuse out and started the vehicle and turned on the AC. I then noticed that hot air was blowing out of the passenger vents while cold air was blowing out of the drivers vent. Maybe a coincidence, maybe related. I don't know. Any ideas?
I would replace the horn relay. Should be in the fuse box under the hood. If you have your owners manual can you tell us which fuse you pulled?the owners manual will indicate if the fuse had anything to do with the a.c.