Upon arrival spoke with customer. He explained the issues he was having with downstairs system. We went downstairs, coil is clean no leaks. Wires all tight. Turned gas side on and had major blow back. Pulled burners and found them dirty. Checked heat exchanger and it is very rusted but found no leaks yet. Started checking gas pressure and found the pressure incoming to be 34IWC. Explained to customer this was not a good thing. He is goin to have the gas company check the regulator out. Customer approved cleaning the burners, and would like to know if the heat exchanger would be covered under warranty. Could not make a call out to check. Cleaned burners and tested the system. Got pressures back down but once regulator is fixed gas pressures will need to be checked again. Blower is clear, indoor is working well. Upstairs attic, coil is clean no refrigerant leaks. Wires all tight. Drain is clear. Heat strips amp within specs. Blower amped at 1.1amps. All duct is tight. Went outside, down