My Carrier furnace (nat.gas) makes a squeaking noise when the blower starts. It will squeak for about 3-5 seconds, then stops squeaking. Everything works fine from that point on. It has done this for all the three plus years we've lived here. I'm handy enough to fix it; just not enough to figure out what the exact cause is. Here's the fun part: this only happens when I'm running the heat. It doesn't happen when the AC is kicking in. I really think it's the belt on the blower/motor that expands with the heat, but corrects itself as the blower gets up to speed. If it's the belt, I'm having a hard time finding a place to adjust the motor or blower. If it's a bearing in the blower (another small possibility), I'm wondering about a port where I can put in some lubricant. It obviously hasn't bothered me enough to mess with until now, but I'd really like to figure this out. Hope you can help me on this.