My heater blower is working but won't blow hot air. What can be wrong with it?

What is your question?

The heater blower is working but won't blow hot air. The engine is not running hot. Nothing leaking in the floorboards. What may be wrong with it? Would it be the heater core or thurmosat?

What makes this problem better or worse?

No the engine is hot.

How long has your 2010 Ford Ranger had this problem?

Three months