Performed tune up on straight cool furnace r22. Filters need to be changed every 2 months. Checked blower motor and evaporator coil. Evaporator coil is rusty and refrigerant pressures are showing there is a leak in system. Has an 18 degree delta and is still cooling but has a coil saturated temp of below freezing. Let homeowner know about lack of insulation in attic. Checked all electrical indoor and out and everything is working the best it can due to age of equipment. Washed outdoor coil and pressure did not change. Recommendation are iaq to help with biological growth and fight virus. And a condenser refresh with new primary unit electrical control and motor starter and compressor saver. Also wants to rewire the house in the next year