Furnace works fine then turns off when house warms up to temp. will not come back on until I turn furnace off and on . Code flashes one time saying system lock out. What should I do ? Thanks mario

That is a very vague discription of problem. My best guess is overheating. See this (https://www.askmehelpdesk.com/heating-air-conditioning/heating-cooling-maintenance-repair-troubleshooting-frequently-asked-questions-58313-2.html#post269282).