The gas valve on your Trane brand home furnace system – as well as any modern furnace system, for that matter – controls the passage of gas to the burner to make heat. Not surprisingly, the system can't generate heat if something’s amiss with the valve. Properly diagnosing the gas valve as the possible culprit is paramount to getting heat back into your home.
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Fire up your furnace if possible. If the unit isn’t running and has recently stopped mid-cycle, wait a few minutes and then feel the outside of the unit with your open palm: If it’s warm, the pilot light is still on, and the culprit isn’t the gas valve but more than likely is the thermocouple. If the side of the furnace is cool to the touch, the heating problem is related to the gas valve, but you’ll need to do some further sleuthing to determine if it’s the only problem.
Check the igniter to ensure there’s gas flow, at least to the valve. If no gas is present, spent wiring on the igniter is possibly the problem or is contributing along with the valve to hampering heat into the home. If holding a voltmeter next to the igniter’s wiring proves everything’s fine with it (set the unit to 110 voltage) or the igniter feels loose in its moorings, you’ve narrowed down the list of “suspects” behind the issue at hand.
Check the condensate drain on the condensate pump, which causes the control board to not do its job. If the drain pump is clear (you’d be able to see any blockages in the line), use the voltmeter to check the wiring on the board. If nothing’s amiss with control board, you’ve finally narrowed down the list to pinpoint the cause: bad gas valves.
- HVAC Troubleshooting Manual; J. Fletcher
- HVACforBeginners.com: Furnace Troubleshooting
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