So I went down stairs to quickly grab something when i heard and odd sound coming from my furnace. It sounded like a grinding sound and it stopped a few seconds before you could hear the burner kick in. The furnace itself ran fine and heated fine, but I popped the front off and could see it looked pretty dirty. So when the furnace was done running I blew out alot of dirt and dust with my air compressor and waited for the furnace to come back on and I took a video this time to capture the sound. Only this time the sound only lasted about 1-2 seconds before it sounded fine again. So I let it run and waited for it to stop and turn on again later..... same thing. Only lasted about 1-2 seconds. Which is odd cause the first time I heard the sound it could have been doing it for upwards of 2 minutes since it takes roughly 2 minutes before you hear the burner kick on. Either way here's the video. Listen closely, it happens right at the beginning in the first few seconds then goes away. But it sounded like rattling/grinding and it was going for quite a while the first time. You can hear it right before I move my phone. [video]https:/vid.me/uc2P[/video]

First time poster since I usually lurk to find answers, but now I have a problem I can't find a good solution for. I have an old Trane model GUEDA-09-A forced air gas furnace with a Honeywell dail-type fan/limit switch (can't see a model #) and a Johnson Control G600AX-1 ignition control module. My problem is that the furnace starts up as it should and starts blowing fine. But, after a few minutes, the gas valve kicks off and on quickly. How much it kicks is very random. It may kick every once in a while during a cycle or it may kick off and on several times in a row before staying on through the rest of the cycle. After looking around and finding that the flame sensor can be a problem for many things, I cleaned it up. Not the solution. I then tested the microamps on the flame sensor and everything was fine until the gas valve started clicking several times at once again and found that there where no microamps in the second that the gas valve went off. So, I'm kind of at a loss as to exactly what it is. The gas valve was just replaced a year or two ago. The Honeywell limit switch is set right and not going over limit. The only thing I can think of is the Johnson ignition module but don't want to drop a hundred bucks or so for one if I don't need it. I wanted to test the voltage on it, but it happens so randomly that I sat there waiting for it and it didn't happen. Anything I'm missing?