could be an air lock in cooling system could be vac operated valve faulty sticking
Have you checked the heater core? It's happened to me before.
if its in the reservoir it should be in the radiator of it is then it has a blow head gasket or a crack head
Leak in heater core. Replace core.
The front expansion valve is clogged.
heater core possibly plugged and leaking
It doesn't really blow it out it just warms the cold air.
heater will not blow on a 1996 ford contour
if the heater does not blow out warm air change the setting.
No! Thermostat.
Could be a bad thermostat.
it has a partially clogged heater core.replace the heater core
Low coolant in the system. Defective heater control valve. Clogged heater core.