Strange sound when heat/AC controls in Auto mode

[dpecorella]

When the environmental control is in Auto mode....there is a strange sound (somewhere between a gurgle and a rattle) coming from the vents. The sound completely goes away when in Manual mode. The dealer says its the blower and wants $300 to fix...but that seems implausible given that the noise only occurs in Auto mode. Any thoughts??

[fueler]

The difference between AUTO and ECON is that AUTO engages the A/C compressor.... you are right, blower motor would make noise regardless of whether compressor is on or not, pop the hood and see if you hear the noise coming from the AC compressor in AUTO vs ECON