One system Concord high efficiency up flow gas heating tune up, maintenance, filter rotation, safety inspection, performance evaluation. Owners are concerned about cooling mode recently Resurface flame sensor and test hot surface ignitor Run test all heating safety circuits Run test gas heating mode Water flush heating drain system Shop-Vac furnace, filter rack, and blower compartment Electronic sniffer test for combustible gases on the furnace gas line 65° heating temperature rise at 135 59° and dropping supply temperature in cooling mode Found bad wiring on the AC control circuit inside the gas furnace. System appears to be running and fair to good condition considering light buildup on the outdoor unit Recommend cooling system PMI with refrigerant pressure testing and condenser coil cleaning