No heat. Cycled system furnace fan and ventor motor both run. Giving code of 4. Checked and cleared condensate trap. It was plugged. Also, found pressure switch was not making. Cleared all pressure lines and removed intake venting. Pressure switch would work if pressure was put on the top of it. Recommend replace pressure switch. Adjusted hose and pressure switch held. Office to quote pressure switch replacement and schedule furnace clean and tune. Furnace is heating at this time. Office to schedule ac clean in spring. Job complete.