Green spot thermostat has blown twice and the pair of thermostats have been replaced twice, when replaced it works for a short time on hot then goes back to cold . Fan works, drum tumbles, just on cold air. All vents and filters cleaned. Cannot afford to keep replacing parts, could it be the element, or the dryness module, or the control knob panel? What colour wires go to thee thermostat with the green spot? any ideas welcomed ??