Preformed routine furnace maintenance on Lennox heater. All components checked out properly, amps in range on inducer and indoor blower. Gas fitting are secure and sealed. Temp rise is at proper range. Flame sensor was slightly dirty but cleaned. filter needs to be swapped out ASAP. Client has order one and will install. Upon departure system is fully operational and Heating home. Need to renew ESA to continue maintenance client was in working meeting.