Came out for no heat call on 1993 Rheem 80% Furnace with 2005 R22 Trane AC. Upon arrival tstat set for heat and furnace was running but very loudly. Can hear humming noise when blower runs then gets louder then burners shut off. Found failing blower motor as well as board with intermittent issues. When calling for fan only board is receiving proper 24v but not giving out 120v for motor to run. Runs fan in heat mode until motor gives out then it shuts off. Found very rusted heat exchanger and burners. Found excessive dust build up on blower fan and cabinet. Also found minimal dust build up on evaporator coil however it is showing evidence of bacterial growth. Main recommendation is to have Install Supervisor come out to discuss new system options due to age and condition of current equipment. Also recommended signing up for our 2 System Home Care plan for 3 annual visits, priority service, and 10% discounts on our services. Customer agreed. Signed up for 2 system plan and also scheduled