Found furnace locked out: 2flashes. Found flame current very weak. Cleaned flame sensor and tested: 2.2uA. Found blower dropped out apoun engaging stage 2 heat!! Corrected wiring of blower. Inducer: 0.32/1.04A. Blower: 3.9/5.1A. Checked temperature rise: 30/48. Checked draft: 0.04”. Does not appear to have proper flue liner in masonry chimney. Suggestions: Furnace is about 22 years old. replace furnace soon. Recommend installing new flue liner to protect chimney.