Cleaned & checked gas furnace. Inspected heat exchanger & flue venting. cleaned burners & flame sensor. Checked voltage & amp draw of motors. Test capacitor. Replaced air filter. Blower: 3.8/4.7A . Inducer:0.09/0.21A . Gas pressure: 1.9/3.6 inches water column. Found basement pressure negative (-.006 inches water column) due to leaks in return-air ducting. Suggestions: return ducting air leaks can be sealed with caulk and tape. Keep basement door open for make-up air to keep pressures balanced. Set fan to “auto“ position when in cooling mode for proper humidity control. Recommend whole house humidifier installation: $716. 15% PMA discount applies.