Could be a number of reasons, including normal operation - if your car has Automatic Temperature Control or Semi-Automatic Temperature Control. Or it could be a problem with the blower itself or the circuit which runs the blower. Working on an AC system is generally not a do-it-yourself task, and there are several reasons why. I'd recommend you have a shop take a look at it.
possibly or i could be the blower which you can get of eBay or any car places such as: Halfords
try wiggling the wires at the blower resistor if don't work then tap on blower motor
the blower motor resistor is bad or the connector going to it
if its a car, your head gasket may be blown. watch out for boiling coolant
Might be a bad heater control
The blower motor speed resistor is burned out.
The problem is either the blower motor resistor or the blower speed selector switch.
replace the resistor pack on the fanblower, under glowecompartment
they dont
I dont know :D I dont know :D
To remove a dead mouse from the car air conditioner fan, it will be necessary to remove all the air ducts by the fan or blower. Removing the blower might allow access to the dead mouse without tearing all of the duct work out.
it is the blower motor resistor. it works on high because on high it bypasses the switch