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rack04 · Dec 1, 2009, 01:52 PM

The spark ignitor on my furnace keeps "clicking" when in use. I took off the cover and found that even while the gas furnace is lit the ignitor is still sparking. Is this the sign of a faulty ignitor? If so, is this fairly easy to swap out?

hvac1000 · Dec 1, 2009, 05:50 PM

Exact brand and model number of unit?

Many times the older spark unitw will keep sparking because the flame is not being completely sensed by the control. Ignition controls and a picture would also be helpful.

rack04 · Dec 1, 2009, 08:38 PM

Originally Posted by hvac1000

Exact brand and model number of unit??

Many times the older spark unitw will keep sparking because the flame is not being completely sensed by the control. Ignition controls and a picture would also be helpfull.

The cable to download pictures from my camera is packed away so no pictures unfortunately. The brand is Carrier and the model is 58GS100-CA.

hvac1000 · Dec 1, 2009, 09:31 PM

It is a good possibility that the three wire pilot is causing your problem but it should be tested since the replacement is at least 75.00 and up for the part.

rack04 · Dec 2, 2009, 06:37 AM

Can you explain how to test the three wire pilot?

hvac1000 · Dec 2, 2009, 07:00 AM

Here is a wiring diagram with the three wire pilot shown. You can test the 3 wire pilot assembly with a ohm meter for open or close. Another trick is to tap on the body of the three wire pilot while in operation to see if it stops sparking.

rack04 · Dec 2, 2009, 12:03 PM

I will try your tapping suggestion tonight when I get off work. If the sparking stops when I tap it does that mean that the pilot needs to be replaced? If so, where would I find a replacement pilot for such an old furnace?

rack04 · Dec 2, 2009, 12:19 PM

I did a little searching and found this video which looks identical to my gas furnace. In the video you'll notice the 3 wire pilot stops sparking a short time after the pilot is lit. On mine the sparking continues throughout the heating cycle. Before we moved into the house I had a Honeywell Model # RTH7600D installed. I don't know if the new thermostat has anything to do with the problem.

YouTube - Carrier 58GS Furnace start up

hvac1000 · Dec 2, 2009, 02:25 PM

I doubt if the thermostat is the problem. I have no idea what the video is supposed to tell since that unit seems to be working OK. I believe you will find your problem as I have already mentioned in my first reply and the only other item it could be is a loose or bad ground at the spark box.

KC13 · Dec 2, 2009, 05:24 PM

I saw a service bulletin addressing this issue a while back. It suggests removing the spark lead at both ends, clipping off about 1/4" from each end, and re-installing it. This will renew the flame sensing circuit to the spark module. If main burner operation is achieved, the pilot/sensor assembly is not the problem.

rack04 · Dec 7, 2009, 01:18 PM

After days of pondering I decided to leave it to the "professionals". Called American Home Shield and they are dispatching a specialist to diagnose the problem and determine if it is covered under the contract. Hopefully it's just a wear and tear issue.