Performed preferred customer furnace safety inspection. Cycled the furnace. Checked the heat exchanger. Found some heavy rusting inside and on the outside of the furnace heat exchanger. Checked the electrical. Cycled the furnace and performed a furnace combustion test. Checked for co in the air stream. Found none at this time. The furnace is 17 years old, average life of a furnace 15 years. Recommend considering replacing due to the age and condition. The customer will wait to replace the furnace at this time. Performed preferred customer air conditioning inspection. Checked the indoor coil for leaks. Checked the electrical. Found a worn compressor contactor. Cycled the air conditioner and checked the refrigerant levels. The refrigerant levels look ok. The air conditioner is also 17 years old. Recommend considering replacing the air conditioner due to the age of the unit. The air conditioner is running at this time.