Hello, troubleshooting a Gemtech 5000B thermostat, Nordyne P3RD-030K package unit. System is approx. 2 years old and has functioned well. Current symptom is in heat mode the blower will not operate in Auto....heat strips are activating as fan can be run in manual and blows warm air. Seems like a thermostat problem but I'm not much good at troubleshooting digital...any suggestions would be appreciated.