either your heater core is shot or the temperature switch in dash needs replacing I had a 1986 Nissian Pickup that had the same problem when I purchased it back in 1988 in Phoenix, AZ.
I figured this out driving thru the Rocky Mountians on my way to Ft. Knox, KY. The heater had been running for about an hour and I was still cold (good for staying awake). I looked under the hood and found the problem.
I hooked it up again and started to drive again and in a couple minutes, I could smell Antifreeze.
The old owner had by-passed the heater core because it had a leak. Someone may have done the same thing to your Ford. Hope this helps. Good Luck and Remember.
Change Your Mind, Not Your Oil.
There are several common heater problems for a 1997 f150. A stopped up or leaking heater core, bad thermostat or clogged up blower fan housing all can cause heat problems.
The variable resistor has probably gone bad
How do I locate the heater blend door actuator in a Ford f150 pickup
The head gasket is about to blow.....Typical ford..
heater core hoses not hot
Try flushing the coolant system out
what is the year model? 1995
Take it 2 a mechanic. :D
There are a couple of a reasons why a 1994 Ford F150 truck will not start. The truck may have a dead battery or the spark plugs need to be replaced.
The headlights in the Ford F150 may have stopped working due to a bad fuse or bulb. Check these and if it doesn't fix the problem visit a mechanic.
It's the block heater. I had the same problem.
The most common cause of this failure is a broken blend door. Check heatertreater.net for diagnostic information and an inexpensive fix.