did 2 preventative maintenance on heat pumps.m# CB26UH-048-230-1 s#6008C26946 During the maintenance I checked the drain to make sure everything was draining properly. Amped out the heat pack to make sure that that was working and it was. Went outside to the heat pump check temperatures and pressures and over in specs of the units spec sheet. Humidifier was not working. Changed out the 18 x 20 x 1 filter system is operating properly the outdoor unit is very old and customer knows he is on borrowed time. M#CBX27UH-024-230-6-02 s#1614D03338 during the maintenance I changed out to 20 x 25 by one filter also made sure that the drain was draining properly. Amped out the heat pack and it was working properly looked over the whole unit and made sure all wire screws were tight secure. The outdoor heat pump the temperatures and pressures are spot on and the unit is working properly at this point. Custom