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?