Arrived on site to diagnose a no heating system on a 2006 aireflow. Client stated system has been down for a couple years. Advised client i would inspect system of issues and see what’s going on. Inspected all electrical compartment and found system giving error code of bad polarity and found pig outlet bad as it wasn’t send proper voltage to system to operate properly. Also found something stuck and broken in side the outlet as well. Advised we got system operational and ran system for a bit and shortly after had all smoke detectors and carbon monoxide detectors all go off in home and we shut system down. Advised client of finds and we would do a safety evaluation of the system to ensure system would be safe to run. Pulled heat exchanger out and found system was leaking and heat exchanger is now compromised and no longer safe to run and we would have to shut gas off to system for safety reason as compromised heat exchanger is not safe for anyone in home and could risk allowing com