Heater fan on full blast all the time
Q. is it the resistor or
Q is it the switch
If it can’t be turned off it’s the switch.
If it runs only on max speed it’s the resistor.
It’s the switch.
The resistors are only for the low speeds. On high speed the voltage bypasses the resistors and voltage is applied directly to blower motor by the blower relay.
So that means the switch isn’t causing the blower relay to send the voltage thru the resistors.
Tester