Arrived on site to perform diagnostic on 10 year old system. Met with homeowners dad, homeowner was at work and only available through cell phone. System is not heating. System will heat for about 3 minutes and then shut off, and only cool air will come out of the vents. Will do this for a couple cycles until eventually it does nothing. Filter is clean. Cycled system for heat. Error code 33 comes on board which could mean a restriction. Verified that all vents in the home are open. Opened up coil compartment and found evaporator coil is extremely clogged, which is causing a restriction and causing unit to over heat. There is no room to remove coil to properly clean it as it is heavily clogged. Blower wheel and cabinet is also extremely dirty, and blower motor has been working extremely hard and has leaked out a significant amount of oil and amperages are high. Went over findings and recommendations with homeowner over the phone. Spoke about repair options as well as the possibility of