Found main level furnace not heating. Furnace was displaying 3 blink code indicating pressure switch issue/stuck open. Technician was able to unstick pressure switch and get furnace to operate. However, it is likely this will occur again. And new pressure switch has been ordered from manufacturer and our office will reschedule return visit for installation once it is received. Estimate has been created and provided. Customer asked to have other two units operations checked upstairs and basement heating normally.