Heater blows cold air. on 1997 Ford F-150

When I turn the heater on regardless of how long I let the Truck warm-up it still blows cold air. How big of a repair job would this be?

2 answers
is engine coming up to temp on the gauge if it is not a thermostat in the engine needs replacement under 50$ if it is warming up the blend door motor has most likely falied 150-200$ ?? it is under the dash on top heater box
The repair will depend on whats wrong with the heating system. This no heat issue could be caused by low coolant level (may be a leak involved if so) and/or a plugged/clogged heater core.
Have you truck checked- the sooner you do the sooner you'll have heat!