The temp is currently 71 inside-- I adjusted desired temp to 65 a half an hour ago and the furnace is still going. Sometimes heat blows, sometimes cool. This has been happening all night. I can't locate the reset button. Unit is at least eight years old. Batteries seem OK-- no LO BATT message. Normally unit will click on/off with desired setting change but not now. I just turned unit on for the first time 2 days ago. Any tips? Thanks.