Did a maintenance on a duel fuel system. Did a combustion test the ppm was 34 and the o2 was 11. Cleaned the flame sensor did a amp check on the blower motor and inducer motor. Both are in range. Also checked temperature an pressures on the heat pump and did a amp check on the fan motor and compressor. Cleaned drain the the high efficiency furnace. Changed out the 16x25x1 filter system is operating properly at this time. m# 59SC2C100S211120 S#3818A63046 customer would like a maintenance agreement she said she would mail check to the office for it.