Performed heating maintenance on a Carrier two stage 96% efficient natural gas furnace Aprilaire 210 filter is in good condition, no need to change for 3 months at least Aprilaire 600 humidifier functioning properly, no water leaks bypass damper open to winter setting Pulled and cleaned flame sensor Condensate trap is clear Blower is clean Set gas pressure High fire 3.2"wc with a 55⁰ temperature rise Low fire 1.3"wc with a 46⁰ temperature rise Initially during testing the heat, control board was throwing a 23.4 fault code: low pressure switch stuck closed and would not energize the inducer After much trouble shooting, it started working for no explainable reason. Construction warranty expires tomorrow We will order a warranty control board, no labor charge will be incurred.a
