No heat. Heat starts but goes off in seconds. Flame sensor was dirty. Also, filter was impacted and case heat exchanger to over heat. Heat exchanger has some hot spots and can develop crack anytime. Evaporator coil is covered by biological growth and blower wheel very dirty. Furnace is 11 years old (single speed) and ac from 1993 (r22). Due to the age and conditions of the system, highly recommend to upgrade the system, and bring safety, comfort and efficiency back to the house. New systems come with 10 years warranty and WiFi thermostat. Set a lead to quote upgrading for today after 4 pm. We should credit 155,00 spent today, if customer upgrade the system.