Upon arrival customer stated that heat had stopped working last night and was only blowing cold air through vents. Gas furnace is 12 years old, ac and coil is 12 year’s old. After inspection of system found that unit had a bad control board the control board was not allowing heat cycle to run properly and would keep activating the blower relay and relay would continental clicking at control board. The harness hit is very corroded and the slightest touch to it would blower the fuse on control board. Unit has had water damage the thermostat wires are very corroded and the control board. Blower wheel is very dirty, blower motor capacitor test ok. Inside system is very dirty. Flue pipe is installed improperly and held together with tape. Drain line lays flat on ground and once it goes to exit point it’s running up hill without the proper elevation to drain correctly. There is no flood protection on equipment. Out door condenser coils are very clogged and dirty, outdoor capacitor and contac