Performed furnace maintenance on 2006 two system Carrier Heaters. During my maintenance I found a few safety concerns and points of failure that may occur. Downstairs furnace- 1. Inspected heat exchanger and found that stamps have cracked due to Airflow restrictions and over heating temperatures over time. Performed hydrotest to confirm that stamps are cracked and verified that all three cells On the heat exchanger assembly are compromised. Due to the heat exchanger becoming compromised there is a potential chance Combustion gases Could enter the airstream once the blower motor turns on. 2. Measure static pressure and found a total of 0.69wc. Recommended manufacture Airflow is rated at 0.50wc. 3. Temperature rise Measured at 57° manufacture specifications rated at 60. 4. Scroll Wheel was covered in dust and debris due to 1 inch filters not being swapped out consistently, recommend to do every one to three months. 5. Indoor blower motor hod oil leakage coming from bearing, The lubrica