You need to measure the pot output voltage at each desired flap position. Then you could use a number of comparators, such as an LM339 to control the motor voltage on and off in response to your switch settings and the pot position voltage. You may need a little logic circuitry to get it all to work properly. Do a state table of all the switch positions you need and what result (flap position, AC on/off, etc.) you want for each position. Then go from there.
Post the state table in this thread if you need further help.