My Carrier Furnace is continuously blowing and the heat doesn't work. The code was first, Limit Circuit Fault, tnen after changing the filter, it went to Limit Circuit Lockout -- and it is still blowing cold air. (Yikes!! It got down to 10 degrees outside)

Click here (https://www.askmehelpdesk.com/heating-air-conditioning/heating-cooling-maintenance-repair-troubleshooting-frequently-asked-questions-58313.html#post268203), go to General #8 Is my furnace overheating? It also shows you what the main limit looks like.