Heater will not blow hot air.
If the thermostat fails to close, which can happen if the sensing element binds up, the return spring breaks or a piece of rust or debris jams it open, the constant flow of coolant through the thermostat will prevent the engine from reaching normal operating temperature. This can cause poor driveability in cold weather, a sharp increase in fuel consumption, little or no heater output, and accelerated blowby and ring and cylinder wear.
The thermostat is probably stuck in the open position.
Thermostat is most likely stuck in the open position; replace the thermostat.
Yes, if stuck in the open position.
possibly thermostat stuck in the open position?
That is the most common symptom of thermostat stuck in open position.
If the thermostat is stuck in the open position, there is no way to keep it from staying open except by replacing it.
Replace the coolant thermostat. It is probably stuck in the open position.
The car's thermostat is bad and not working. Most likely the thermostat is stuck open. Thermostats are heat sensitive valves that open and close. If stuck in the open position the car never warms up. If stuck in the closed position it will over heat. http://auto.howstuffworks.com/cooling-system8.htm
Check the coolant level. Or, thermostat could be stuck in open position.
Thermostat stuck in the open position. Replace the thermostat.
Usually the car would run cool, unless the thermostat is stuck partially open.
If your engine takes a much longer time for the thermostat heat guage to reach its required level of operatiing temperature then the thermostat may be stuck in the open position which means that it will need to be replaced.