Heater/defrost fan keeps running

[CaliLivn]

This is for my dads 74 pickup. It has 350, AC an everything. The other night when he got home he turned off his truck an the heater fan kept running. He started his truck real fast an shut it down an it still kept blowing air. He got nervous so he popped the hood an unscrewed the battery cable an it shut off. In the morning he reconnected the battery cable an it started blowing air right away. He tried starting his motor an shutting it off an removing the key an it stayed on.... Finally he pulled the heater fuse an it stopped. Has anyone had this happen before? I would like to try an fix it myself before taking it to a shop. Thank you

[wilkin250r]

The fan is designed to run any time the ignition switch is on, the fan doesn't really have an "off" position. So my first suspect is the ignition switch is old and worn, and isn't turning off properly.

Do any of the other accessories work, like radio, lights, and other accessories that are also on when the key switch is on?

[CaliLivn]

Originally Posted by wilkin250r

The fan is designed to run any time the ignition switch is on, the fan doesn't really have an "off" position. So my first suspect is the ignition switch is old and worn, and isn't turning off properly.

Do any of the other accessories work, like radio, lights, and other accessories that are also on when the key switch is on?

That was my first thought. I had him go try the radio with the key removed an he said the radio didn't turn on. He even put the key in an turned other truck on an put the radio on kinda loud an leave it on as he turned off the truck an the radio **** off. He's gonna put the fuse back in tomorrow after church an see if it healed itself. Lol