I've searched and can't find one.

Bought the car not to long ago so I dont have history on it. IT's gone like this:
Heater fan wasnt working so I traced things downa nd the resistor was missing. Replaced it and the fan came on one speed only and was very slow and sound like shot bearings so I replaced it. Did not note the position of the switch how ever when the fan came on. (critical info maybe).... replaced motor and it blows your hair back.. BUT it only works on hi and with the switch in the off position ???? Then I was driving with it going for a while and it suddenly stoppped working again. the fuse is good the connections are all good. ??? I was going to run a lead to check and see if the motor is still good but I did not smell a burnt electrical odor before it stopped working.

Where can I find a heater fan switch? What else could it be? Need help this is my daily driver and its winter time and I need the heater/defroster to work. Can I use a switch from another car like a 71 chevelle?