it's because of heat transfer into convection .
heater switch needs replaced
The heater does not blow air because it emits infrared rays that have heat molecules within them, thus releasing heat, not blowing it. A heater does not blow air becasue there is no moving air source within the heater. The heater emits infrered rays that cause heat to slowly flow out of the heater.
heater will not blow on a 1996 ford contour
if the heater does not blow out warm air change the setting.
perhaps because the engine running heats coolant that cycles through the heater core and has air blowing across the aluminum to exchange the heat into the air that is forced through the vents
Low coolant. If the coolant is low then the heater core is not able to transfer heat in to the car.
Because your thermostat is probably stuck open
Because it is dirty and needs cleaning and/or it is overfired.
Because the resistor between the heater swithch and the heater motor is not functioning. Usually mounted on, in or near the heater enclosure. Its a common repair, and can be done by the do-it-yourselfer.
Your heater will blow cold air only.
The air alone is not able to blow up a balloon. When air in the bottle is heated with a balloon on top of it, the air expands due to the heat and moves and finds more space. This in turn will blow up the balloon.
First, check your rad level, possible heater core plugged, vent door problem, feel the hoses at the firewall where the heater core is, if they both feel hot it is not hte heater core, rev up the engine to 3,000 rpm... if it heats up it could be a bad water pump!