Hello, everyone.

I have this power vent kit on my gas furnace:

http://www.fieldcontrols.com/pdfs/46285100.PDF

Actually, the vent itself is different, but the control box is the same.

Sometimes my thermostat turns on the furnace, but the control box won't turn on the blower. I had a repairman come out a couple years ago, and he simply tapped on the box and got it working. He said the sensor in there can get gummed up in such away that it's not sensing that the vent is working. Tapping it can ungum it. I've done that successfully a few times since then, but it's a hassle to go down in the crawl space, and I'm afraid it will happen in the middle of a cold winter night or when only my wife and baby are at home.

How can I fix this so I'll never have to tap that box again?

I pulled the main cover off, and the wiring looks secure on the terminals. I didn't know how to get the cover off the Honeywell cylinder on the side, which I think is the pressure switch. I also wasn't sure how to disconnect the white wire from that cylinder. Does it screw off or pull off?

It's worth noting that the whole set is about 4 years old, so it was pretty new when this first happened.

Thanks for any advice you can give me.

Steve.

Actually I never recommend a homeowner that is not a heating service person work on those Field power venters. If you mess something up in the controler you can end up with a major safety problem on your hands. If you are afraid of your wife and baby being left in the cold or in a unsafe situation I recommend you hire a professional to fix the problem correctly and you will feel much better knowing that it was done correctly.