Upon arrival found that system has an I comfort thermostat that is having issues, tried resetting thermostat and screen still blank. System has a communicating xc21 for outdoor unit which makes system true communicating. Thermostat will have to be replaced with a Lennox s-30 thermostat. Thermostat is out of warranty, homeowner approved replacement of thermostat, part ordered at Lennox in Allen order#33731293 Also performed a one system maintenance checking heating, checked all electrical, mechanical, and safety components. Checked amp draws, cleaned flame sensor, and changed out customer supplied filter. Equipment wise everything is operating properly at this time.