Complete 1 system furnace repair and preventative maintenance check. Check and find the main system heating system operating within manufacturer spec but the system was overheating due to high gas pressure. Reduce gas pressure to 3.5" w.c. System operating at this time. Did not detect properly why the system keeps on blower cold air. Find PVC flue pipe run into a double-wall metal pipe. Not code. The find system have no water safety in the basement and a missing drain pan. Need to run PVC flue outside of the house. Need to install water safety and drain.