I have Bryant upright furnace (Model 394GAW048100). Furnce runs fine for the first 4 or minutes in a cycle and then gas is cut automatically while the pilot is still on. After a few seconds, the gas again comes on and Furnace works fine for about 30 seconds, again gas is cut and so on. I changed the Furnace Limit Switch. Once I changed it, the furnace worked fine without cutting gas for the first about 12 minutes but then started cutting gas for about 30 seconds. A minute on and so on.

Is it normal for a furnce to cut gas. Or do you know if this is an issue. If issue, what should I check.

Thanks
John

John it could be your firing valve the pick and hold might not be working right give that a try

Ok I'm a little confused here. What is a firing valve? A pick and hold? Never heard these terms.

The firing valve is the main control that allows gas into the furnace the pick and hold is the way the valve on a bryant furnace works it the way they design it . Troubleshooting should be left to a qualified tech.Firing valves are not cheap.

Odd. In all my years in this industry I have yet to hear that terminology and I'm a Carrier dealer.

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Originally Posted by MarkwithaK

Odd. In all my years in this industry I have yet to hear that terminology and I'm a Carrier dealer.

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Example from my class. Used with 3 wire pilot

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Originally Posted by hvac1000

Example from my class. Used with 3 wire pilot

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Pilot