im new to the vav game< i have a titus vav box, non fan powered 3 stage heat, controller is calling for 100% heat, no control voltage to contactors. line voltage is there and transformer is good. my question is: does the control board send signal to the transformer to on the secondary side to power the contactors. all the safetys are made but still no power? i guess I'm asking how does the controller send the call to the transformer?