heater blows cold air. on 2001 Ford Taurus

Heater blows cold air. I let car warm up before driving but still no heat.

Asked by for the 2001 Ford Taurus
You could have an engine not getting to operating temperature. Check the temperature of the hoses to and from the heater core. Are they both cold? Both hot? Is only one hot? If they are both cold, then you could have a thermostat sticking open. If they are both hot, then instead, you may have an issue with temperature control in the dash (like a faulty temperature blend door motor...). If one is hot and one is cold, you could have a heater core restriction.
2 more answers , 1 more comment
Same problem here. I added coolant and now it works fine.
heater blows cold air, and what is that little black cord that comes out of the right side under the dashboard, it is unplugged, could this be a cause?
Not sure what the cord is; but certainly warrants looking at.