Upon arrival, thermostat indicated the system was heating but the furnace was not operating. System was not showing any current codes. Code history only shows previous gas valve code. Test ran operation of furnace in thermostat heating test on low and high. Both initiated and worked properly for approximately 15-w0 minutes each. Inspected system for any loose wiring. None found. Inspected flue termination for ice buildup or other blockages. None found. Turned thermostat to normal heating mode and system turned on as it should after 5 minute wait period. System is currently operating with no issues found or suspected. After talking with Nate, he suspects it could be a bad control board butnaystem is currently running