Heat rise 26 degrees. Washed air filter. Combustion chamber passed inspection. Tested with powder. Furnace miss fired upon arrival due to rusted burner system. Pulled and cleaned burners. Found that the outdoor refrigerant pumping has failed megaohm test reading 20 megaohms. Recommend replacing furnace and AC due to obsolete refrigerant and parts. Cleaned burner box. Cleaned indoor air circulation system. Flames are blue with orange tips. Furnace was running at the end of the call.