Inspection of HVAC equipment. Signed for new Comfort Club Membership. Doing the heating maintenance first for the first visit, then summer will be prepaid for this year. Replaced clogged filter, checked electrical and safety switches all ok at this time. Did a combustion test and found high oxygen content for combustion. The system is not burning efficiently. Did a combustion calibration for better air and fuel combustion. Found system with a very dirty blower wheel. No sign of water damage to the system. The system is heating at this time.