A furnace blowing cold air usually indicates ignition failure or a safety lockout. This South Lake Tahoe property experienced the same problem twice within a month. Riley Plumbing Heating And Air had resolved it previously, but the condition returned after brief normal operation. The technician checked the flame sensor first. Carbon buildup on the sensor rod prevents it from confirming ignition, triggering repeated safety shutoffs. Cleaning restored proper flame detection temporarily, but the rapid re-soiling suggested incomplete combustion. Further inspection revealed a partially blocked burner orifice causing uneven flame patterns. The burner assembly was removed and thoroughly cleaned. Gas pressure was verified at the valve. The furnace cycled properly through multiple test runs. Recurring problems point to underlying causes beyond the obvious symptom. Addressing only the immediate issue guarantees callbacks. Book your heating repair diagnostic with technicians who investigate root causes rather than treating surface symptoms.
