Furnace runs but produces insufficient heat; rooms do not reach set temperature even though the unit cycles normally.

Safety: Turn off gas and power before internal inspection. Gas pressure and burner adjustments must be done by a licensed technician.

User-level checks:

• Thermostat setting: Confirm the room thermostat is correctly set and not in an economy or setback mode.
• Airflow: Ensure all supply and return grilles are open and filters are clean to allow full airflow.
• Visual burner check: Through the inspection window, observe the flame. It should be stable and mostly blue. Yellow, lazy flames indicate combustion issues that require professional service.

Professional tasks: A technician should measure gas inlet and manifold pressure, inspect and clean the burner and heat exchanger, and verify that the Cointra furnace is correctly sized and configured for the property.