Probably the heater blower motor.
A bad control switch can cause your 2003 Nissan Sentra heater blower to stay on. The motor or a bad sensor can also cause the heather not to work properly.
There is a loose wire somewhere in the circuit - tapping the heater makes the wire complete the circuit !
Why does your ac and heater fan turn off and on
DON'T turn it on.
There might be a bad fuse causing the heater to not work. Check the fuses if they are all ok you may have a bad blower motor. when you turn the heater on and no air is blowing then it is your blower motor.
The blower switch is the knob you turn on the heater control in the dashboard. If you are talking about the blower motor resistor, it is located in the passenger's foot well area, mounted in the heater box.
Common causes, blower motor resistor, blower motor, wiring or controls
My blower doesn't go on when i turn it on can you tell me what is my next move to fix
I have the same problem. what I do is tap on the heater blower (located below the glove compartment in the corner)which will magically make the fan work or remove the two gold Philip screws that hold the cover and spin the fan manually.
when you turn on blower it makes a strong odor of burning rubber.
check the blower motor resistor pack. should be firewall side of heater rectangular connector with 4 or 5 wires.