Your gas heater is blowing cold air The furnace flame will turn on for about 10 seconds then shut off It only turns once every 5 minutes Any ideas?

Here are a few reasons why your gas heater may be blowing cold air and the furnace flame turns on for only about 10 seconds before shutting off, turning back on only every 5 minutes:

* Clogged Air Filter: A clogged air filter can obstruct the airflow and affect the performance of the gas heater. Ensure the air filter is clean and free of debris. Replace it if it's dirty.

* Dirty Flame Sensor: The flame sensor detects the presence of a flame and keeps the gas valve open. A dirty flame sensor may not properly detect the flame, leading to intermittent ignition. Clean the flame sensor using a soft cloth or brush.

* Malfunctioning Thermocouple: The thermocouple is a safety device that senses the temperature and prevents gas buildup. If the thermocouple is faulty, it may not accurately detect the temperature, causing the heater to shut off. Check the thermocouple and replace it if necessary.

* Defective Gas Valve: A faulty gas valve may not properly control the gas flow, leading to intermittent ignition. Check the gas valve and ensure it's functioning correctly. If it's defective, consider replacing it.

If you're uncomfortable performing these checks yourself or suspect a more complex issue, it's best to seek the assistance of a qualified HVAC technician for a thorough diagnosis and repair.