Dual Fuel system at 10 CO ppm and 12% O2. Made slight gas valve adjustment to bring O2 down. Gas valve falls to 0 ppm on shutdown. Checked charge in cooling mode. Burners are clear. Inducer sounds good. No over amping from system. HP system had a dirty filter. 18.4 F delta T in cooling mode after removal of dirty filter. Checked all capacitors, amp draws, and voltages. Systems are functioning normally.