The #1 cause of cold air from the heater when the car is stopped, or the engine is idling, low engine coolant levels.
heater switch needs replaced
Most likely your pilot light is out
Check to see if you pilot light is lit
THE CAUSE for this is that when your cold air is on the petrol is used to create air. and that is how cars create cold air
The heater may not be on - but the fan still blows air through the vents when they're open !
Possible causes are, low on coolant, thermostat stuck open, clogged heater core or vacuum scorce not getting to the heater control.
Blowing out moisture is a sign that the heater core is leaking. Starting out hot and turning cold could be low on coolant.
Low coolant, bad coolant, blockage in the coolant line, bad heater core or element, bad thermostat
Low coolant level? Thermostat stuck in closed position? Water pump not circulating coolant? Cooling system airbound?
it is used with a small heater to heat the water in the engine for easier starts in very cold weather
Low coolant. If the coolant is low then the heater core is not able to transfer heat in to the car.
If it is broken. It could be a faulty temperature blend door actuator.