No gas on Carrier furnance


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Old 12-27-07, 02:56 PM
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No gas on Carrier furnance

I have a Carrier Weathermaker I (Model # 48DJD005500)(approx. 20 years old). The gas is not coming on even though the igniter is sparking. I have this same model/unit on the back of the building. I exchanged the igniter and thermocoupler but did not fix the problem. The inducer motor comes on, then the blower motor, then the igniter tries to light the gas but I hear no gas (hissing) and I smell no gas. I used this forum last year and was able to replace a board to fix the AC portion of the unit. Any suggestions would be greatly appreciated.
Thanks
 
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Old 12-27-07, 03:01 PM
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Originally Posted by Bogart
I have a Carrier Weathermaker I (Model # 48DJD005500)(approx. 20 years old). The gas is not coming on even though the igniter is sparking. I have this same model/unit on the back of the building. I exchanged the igniter and thermocoupler but did not fix the problem. The inducer motor comes on, then the blower motor, then the igniter tries to light the gas but I hear no gas (hissing) and I smell no gas. I used this forum last year and was able to replace a board to fix the AC portion of the unit. Any suggestions would be greatly appreciated.
Thanks

Well, if it has an ignitor it doesn't have a thermocouple, and vice versa.


An ignitor is like an electric glow plug that lights the gas. It might also have a pilot switch to light the gas, which has a "tick, tick, tick" noise as the spark lights a pilot light.


Do one of those describe your system?
 
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Old 12-27-07, 03:09 PM
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Yes. It has a tick, tick, tick. I can see the spark trying to ignite the gas.
 
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Old 12-27-07, 03:30 PM
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Originally Posted by Bogart
Yes. It has a tick, tick, tick. I can see the spark trying to ignite the gas.
Things that can cause this problem are---


no gas to the house (meter shut off)

gas shutoff valve at the furnace turned off

Electric gas valve control knob turned to off position

Plugged pilot orifice/dirty pilot burner

burned out or defective gas valve

defective pilot switch not turning voltage on to pilot valve



Check as many of those things as you can.

To simplify things, you can disconnect the pilot tubing at the gas valve and see whether you've got gas coming out of the gas valve when the spark is trying to light the pilot. Keep a thumb over the gas valve outlet and remove it briefly to see if gas is coming out.

And is the electric gas valve on the furnace more or less a cube, or a relatively flat rectangular solid with a blue (usually) control knob?
 
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Old 12-27-07, 05:20 PM
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How about lighting pilot when you hear the spark. If it lights, only may need to clean pilot. If it does not light, probably call for service after you have verified all Seattle said.
 
 

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