Issue that customer had did not occur while we were here but to here from them what was going on sounds like a temperature limit fault. House is still under going construction. I lowered gas pressure down a tad to 3.2 in wg. Informed customer to keep up with filter changes to ensure good airflow. Also showed customer how to read fault code for furnace if issue arises again. Found a bat in furnace and a squirrel in another. Set customer up on maintenance plan.