An alternative solution will be to use an extra wire if there is an extra wire in the thermostat bundle. If not, then you will have to pull a new thermostat wire from the furnace to the thermostat. If you are lucky, you will find the problem there. In this case, the red and green wire would be touching somewhere in the bundle.įor a quick check (and hopefully to resolve the issue), check the thermostat wire terminations at the thermostat and the furnace. When the insulation is gone, the wires touch inside the thermostat wire bundle. Older thermostat wire can have degraded insulation.
For one reason or another, two wires are touching one another and keeping the circuit completed with no control. This is basically what some people would call a shorted circuit.
