Performed the level 2 package cleaning. Furnace: Burners and ignition are showing signs of wear. Heat exchanger is very rusted and chipped. No cracks located in the heat exchanger and no CO detected in the air at this time. Combustion readings were normal. Drain is clear. Heat rise was 41°. AC: No leaks detected. Electrical components tested good. Condenser coil is clean. Refrigerant pressures were good. Subcool and temp split were 15°. I made note that the unit is starting to sink into the ground. This may be more difficult and expensive to fix in the future. All equipment is operating properly at this time. I recommended annual maintenance in order to keep an eye on everything concerning.