Fan for heater not working

I can a feel a semblance of heat but no settings on the fan work. I have a remote start and noticed this morning the truck was not warm when I got in it. I turned the fan switch on and off a coupe of times , but nothing . I went to load the truck and when I came back the fan was on. Now after working all day ,and start/stopping the truck for various stops,it stopped after I turned off the truck and turned it on the last time. I looked at the fuse diagram in the owners manual but could not figure out which one it is. The manual does not seem to correspond to the layout I have. I checked the engine compartment and the one located under the seat.