If your heating system is working but not blowing heat, the primary reason could be dirty or clogged filters. The debris and dirt can clog your system’s filters and lead to overheating. Thus, there are high chances that your heat exchanger is shut off and not heating your house. 

In case of clogged filters, you must replace them with a newer one and restart your heat exchanger to get back to your comfort zone. If you do not know how to replace the filters, you must consult an experienced technician for professional help.