I have a an Air conditioner/furnace and needing to connect a booster fan to it. Duct work is run to the location and i have installed a 120 v booster blower and a 24v Electric damper. I am an Electrical engineer but having trouble following the schematic in the furnace. So here is what i need to do. I have installed a switch in my shop which will turn on the 120 v fan and also a 24v transformer (which opens the damper). I was trying to connect this 110 v line to the hvac unit where when the blower came on, (and i had the switch on in the shop) then the damper would open and the booster would run. By having the switch in the shop, I would only turn it on when i was working there. I have attached a schematic. I can not seen to find a single place of 110 v that comes on when the hvac blower is on. I know that you have high speed blower for Air and lower speed for heat. Seems i cant find a common point for 110 ac when either fan is running.

I have even looked at the hvac 24 volt system. I understand the green wire is for fan but is that on for both heat and cool? If so i guess i could install a 24 volt relay which could control the 110 to my aux booster.

can anyone tell me the best , easiest way to connect to a point in this furnace where i will have a voltage if either heat or cool blower is running? Thanks, Tom