This switch costs a fortune to buy nos or good used. I found this out when I restored my dash in my 68 Cuda. Same switch as yours. Mine would only run in high or off mode. I took the back off the switch and found that the old grease in it had hardened up over the years and affected the operation of it. I sprayed it with some electrical contact cleaner , greased it with dielectric grease and reassembled it. Worked perfect after !!
If your switch is not working , it costs almost nothing to try this before you spend money on a new one. Hope this helps!!
I just had the same issue with a 4 way flasher switch. Took it apart and cleaned the contacts and greased it put back together and it works good. Just be careful when you take it apart that no parts fall out and get lost. My switch had a small ball for the detentes and was spring loaded.
I did the same thing with my headlight switch for my 2006 Chrysler mini van. The lights would flicker on and off while driving down the road. Took it apart, cleaned the contacts and regressed it. worked great ever since. Same fix on a newer vehicle and no charge. Some things never change
I did the same at 93 Lebarron. No separate fan switch available. Replacement part is entire climate controller. It was a little more difficult to take apart, tiny springs and contacts inside. Fixed for free.