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Jason Martin
Jason Martin, Handyman
Category: HVAC
Satisfied Customers: 106
Experience:  One year systems installation and repair,
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If flame sensor is going bad, how will my furnace act?

Customer Question

If my flame sensor is going bad how will my furnace act?

Submitted: 8 years ago.
Category: HVAC
Expert:  Jason Martin replied 8 years ago.

If your flame sensor is going bad, the burners will come on for about 5 seconds or less and then go back out. This cycle may continue for about 3 tries.
Is this what is happening to your furnace? If so, let me know and I will tell you how to fix it for free!

Jason Martin and other HVAC Specialists are ready to help you
Customer: replied 8 years ago.

This is happening how do I fix it?

Expert:  Jason Martin replied 8 years ago.

The easiest and most cost effective fix is to clean the flame sensor with steel wool or a green pad. Just scour it like you were trying to give it a light sanding. Just enough to remove the build up.
There is a carbon build up on the flame sensor over time that can prevent the sensor from sensing the flame. When working properly, the flame passes over the sensor producing a minor electrical charge in millivolts. That electricity is sent to the gas valve and allows the gas to continue to flow.
When the sensor doesn't get this flow of electricity, it cannot send the "ok" signal therefore it shuts off the gas.
If you have any more trouble with this, just stop in and let me know.