1999 Ford Taurus 3.0l EFI 6cyl, heater dont work

What have you checked so far ?
Radiator full of coolant ? Heater hoses getting hot ?

unless it is the heater core which you should flush system,,i always boil my new thermostat to make sur it compresses

flush the cooling system, probably clogged. happened to me a bit ago with a 99 cherrokee. hope it helps ya.

if the ac still works and the heater turns on but blows cold air it is the heater core, if it does not blow at all its the blower motor

sounds like your thermostat is stuck open, if its takes a very long time for the engine to warm up and you get nothing but cold air from your heat then thats the first place i would start.

It could be air locked. Feel both your heater hoses, and, with the engine running, loosen the one that's cold, if there is one. If that doesn't help, it is probably your heat control valve that is malfunctioning.

sounds like the controller went bad use temp checker see what your temp is at inlet of heater core from hose

sounds like heater control valve situated under scullle panel common fault on ka set heater fan switch half way between hot and cold with heater blowing then touch valve if pulsing or clicking noise it is faulty if doesnt solve problem faulty switch

Taurus does not use a heater control valve. It runs coolant thru the heater core constantly. You may have a temp blend door actuator problem or a plugged up heater core is also very common. Feel the heater hoses, they should both be very hot, it one is much cooler; you can try to back flush the core.

Have the cooling system flushed or remove the hoses from the firewall(when cool) and blow out heater core with compressed air-clogged heater core..