Had a new Lennox G61v installed this year, and recently, I've noticed a foul odor on the side of my house near the exhaust pipe. There is no odor in the house, and the unit is working great. I realize that that this could be a dead animal or something like that, but I haven't seen anything, and my dogs would be obsessed with something like that. However, I was wondering if anybody else has experienced a foul smell from the exhaust of a high efficiency furnace? By the way, when it is running and I am standing near the exhaust, the smell does not appear to be coming out of the pipe. Could this be furnace issue? I am trying to rule everything out before I call for service, since I assume its a dead animal.