Gas Furnace Problem

Old 10-18-09, 12:49 PM
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Gas Furnace Problem

Today we turned on the Furance for the first time this season. It did not start heating so I checked and the force had stop blowing. As I was working to get it going I heard a buzzing sound for a few seconds and then it stopped.

Unsure of what it was I cut off the gas and the thermostat. The buzzing happen again and has been going on and off since then (first heard about 9:50am this morning).

The pilot is still lit and has not gone off. The instruction mentions a main swith which I can not seem to fine.

Please help.

Mr. Redhawk.....!
Old 10-18-09, 03:16 PM
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Does the blower wheel spin freely with power removed?
Does the blower motor feel hot to the touch with power removed?

If you answered yes twice, you may only need a capacitor.
Match the voltage and microfarad of your existing cap. This is a 5 mfd 370vac example, but blowers usually use a 7.5mfd or a 10mfd 370vac.

Capacitors can hold a charge for a few minutes after removing power, so allow 5 minutes after removing power before touching it.

Caps are usually strapped to the blower.

Old 10-18-09, 03:27 PM
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Most furnaces have a "light" switch near them to remove power.

Would't hurt to also turn of the gas valve..
Old 10-19-09, 12:21 AM
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It sounds like you have an intermittent pilot gas ignition system.

The pilot is lit each time the thermostat calls for heat.

So when you turned up the thermostat, you heard the buzz of the spark to light the pilot. When the pilot lit, the spark shut off.

When you turned off the gas valve, the pilot went out and the spark turned on and has remained on trying to light the pilot.

You can turn the gas back on. The pilot should light again and the spark should shut off. Check to see that the pilot is lit.

The main burner should then turn on. Check to verify that the electric gas valve is turned to the "on" position.

If all that happens as described, you may have a bad electric gas valve or a defective ignition module. What is the make and model on the ignition module?

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