Have HVAC Questions? Ask an HVAC Expert for Answers
Hello the problem could be a loose connection at the thermostat or where those wires attach inside the furnace... or it could be an electronics computer card failure. if you have an electronics repair sterioscopic microscope I can coach you on how to diagnose and repair the micro computer card.
Let me know a lot about your skill sets so that I can coach you most effectively.
We can go from there.