Upon arrival found that homeowner had a E30 thermostat that was showing a blank white screen. Took thermostat off the wall and checked voltages at thermostat, it had 24v and 2.56 dc volts with no electrical interference. Thermostat is under warranty and labor warranty under coil care. New S30 thermostat is on will call at Lennox in Allen. Will need to return and install new thermostat. Upon arrival replaced old i30 Tstat with new s30, turned unit off, installed hub in attic on post, tied all used wires to common, wired in new Tstat, set Tstat up and showed homeowner how to use Tstat. System is now working properly at this time. Labor covered under cool care.