It's located under the dash on the passenger side. There are two clips in the front of the under-dash cover and a Christmas tree type push pin that you will probably have to replace ( I just cut it off with a pair of side cutters). The blower motor is the round gizmo that protrudes downward. If you're having a problem with the fan speed, it's the fan resistor mounted all the way against the firewall. Hard to replace! The part is only $30, possible to replace, but best left to the professionals.
There is a removeable panel below the glovebox. It is in front of the blower motor against the firewall. It has a wire connector from the loom and then it plugs into the blower motor
Loose connection or blower motor is bad
Replace the blower motor resistor.
I owned a 75 model Impala and the blower motor was located under the hood, passenger side of vehicle,down in the fender/fender well area, hiddenbehind a/c unit
faulty blower motor resistor
down uner the glove box
There is only one blower motor resistor and it is located in the evaporator housing.
Right next to the blower motor
The blower motor is under the glove compartment
the blower motor relay is located next to the blower motor it is connected to the motor by a purple and black wires
Under the hood. In the blower motor harness connector.
connection could be loose. Or the switch might be going out