Heat/AC problem, won't change to different outlets

[glock35ipsc]

We have my brother's "new" 2000 running great after replacing the fuel pump and filter, now we have a heat/AC problem. Now matter what position the selector is in (dash, defrost, floor, bi-level, etc) we are not getting air coming out of anywhere. There is a little that can be felt through the floor, but the bottom line is the doors are not moving. The blower will run through all the speeds just fine, but we just can't change the outlet position.

Are these vacuum controlled or electric? I can only guess electric since I can't find a vacuum hose going through the firewall anywhere under the hood.

A little background on this truck..... when the fuel pump went out, the P/O just towed it home and parked it, and it sat for about 1 year. I don't suspect that mice got in the interior, though I guess it's still a possibility. But there was no evidence of mice inside the truck, and there is no smell (you know that smell I'm talking about! ) coming from any of the vents when the fan is on high, nor is there any "mouse house" stuff coming out of any of the vents.

Anyone else had this problem, or know where to start?

Thanks in advance.