A fan heater transfers energy in the form of electricity to a heating element, which then converts the electrical energy to heat energy. The fan then blows air over the heated element, transferring the heat energy to the surrounding air in the room.
the heater blows warm air when fan is on low but blows cold air when fan is turn to higher setting
The heater is like a small radiator(heater core) usually located in the dash. The fan blows air through it and heats the car. There are two heater hoses that carry coolant to & from the heater core.
most likely your heater-core went bad. if you car runs perfectly fine besides having heat. if you car gets up to normal temperatures, doesn't over heat. the fan blows, but just blows cold air. then it is the heater core.
Only blows cold air with the a/c on while driving, your cooling fan or fan clutch is bad depending on the year, make and model.......... Only blows cold air with the heater on while driving, you will have a bad or broken internal a/c - heater control door.....
it could be your fan motor is going to go
Some problem with the fan or related components most likely. the heater core has no moving parts and the fan just blows air through it.
The heater in your car uses waste heat generated by the engine. The hot coolant from the engine flows through the heater core causing it yo get hot. A fan then blows air over the hot heater core into the vehicle.
This can happen if the water or coolant level in the radiator is low. There are other causes but this is the most common.
See "Related Questions" below for a complete discussion on possible causes and more importantly: fixes
because the heater uses hot coolant/antifreeze to heat your car....the coolant passes thru the heater core, then a fan blows the warm air thru your vents Your heater core is leaking and must be removed and repaired or replaced.
the heater blower resistor is bad. located on firewall under heater hoses two 8mm bolts. about a twenty dollar motorcraft part. easy repair.