heater blows cold air on 1997 Ford Explorer

when i turn heat on no heat just cold air

Asked by for the 1997 Ford Explorer
There are multiple reasons you could be getting no heat. First, the engine may not be getting warm enough fast enough. This could be from a faulty thermostat - sticking open. Second, the heater core may not have flow. You might have a hot hose going in, but a cold one coming out. This could be from a restriction. Third, you may have a temperature blend door motor in the dash failed.

Testing is in order to determine your failure. Good luck!
Where is the blend door motor located
Behind the dash, on the heater plenum assembly itself. The dash must be removed to have access to it.