I've had the issue of the burners not staying on and thus the furnace only blowing cold air. If I shut down the entire furnace for a couple minutes, and turn it back on, the gas burners will fully function but only for about 30 minutes.
I know the previous home owner and she said something simple needs to be cleaned. Possibly the flame sensor?
If that is the case I'm not sure where the flame sensor is located, or how to properly clean it.
Photos of behind the access panel. I can take additional photos if needed.
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Polar Bear2012-01-31T12:18:55Z
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This sounds to me like the filter needs to be changed. The burners may be shutting down on over temp. Cleaning a temp sensor should be done very carefully with a brand new piece of scotchbrite. If you don't know what you are doing you could ruin something expensive. Call a qualified tech.
It sounds like the flame sensor does need cleaned. It is located between burners and heat exchanger. There should be an ignitor on one side and the flame sensor on the other. Be sure to turn off the power to furnace, remove the screw holding flame sensor in place, remove flame sensor and clean with a brillo pad or scotch bright pad or brass brush. Re-install and the furnace should be fine. This should be done annually to prevent unexpected shut down.
This sounds like what Polar Bear said-an overtemp issue causing the high temperature limit to shut the burners off. He's correct, check your filter first amd replace if needed. Also a dirty blower fan or a dirty evaporator coil (if it is a central air conditioner) can cause this. The 2 I suggested are more a service tech type of issue, unless you are familiar with furnace fans and cleaning A/C evaporator coils. Good Luck
30 minutes is a long long time.The blower will turn on with no flame to remove any remaining heat.If it runs for 30 minutes and your house isn't warm you better call someone to look at it.