Customer has 10 y/o 2-zone Lennox system that operates for whole house. Furnace located in attic. System was not heating properly due to dirty flame sensor causing system short cycle. Cleaned flame sensor. Also, noticed dirty filter. Replaced 16x25x1 filter. Dampers are operational. Amp draws are within fair range. Blower speed set properly. Ductwork is properly sealed. Blower wheel cleaning needed. Separate zone board transformer is needed. Water protection is poor. Recommend iWave for dust reduction and air purification. Advised customer to signup for HomeCare Program for regular system maintenance. Informed customer of all findings. System is currently working.