Thats because the trap is supposed to have water in it. Its a trap. Without water, your pressure switch is not closing due to no drop in air pressure. Turn off red switch. fill the trap. Carefully pull off, clean and tighten if necessary all spade connectors everywhere. Loosen (Dont Remove) screws on main control board where wires attach one at a time clean and put back, CRC QD electronic cleaner is great here, and usually available a wally world spray and retighten wires. Try all this then turn on switch and have somebody else turn up stat while you look through that site glass there. If the same thing happens, come back and tell us exactly what happened. Turn off lights while you look and listen for clicks and other indicators, and when they occur. Then come back and tell us what you observed. Yuri is correct, of course, but you sound stuck, so we will try to help till you can call in a pro for a complete check up.