My old thermostat had only two wires and they have 24 volts AC to them. Iconnected them to C and R terminals and the display works fine but will not start the furnace. I then used a jumper wire from C to W1 which is the furnace and as soon as the furnace kicks on the display goes blank. Is there anyone who knows how to run the jumper wire to make it work? Ps: Only have a furnace no Air Conditioner.