Hello there, Here is my Problem . I just bought a 2006 Chevy 3500 express. 6.0 V8 . i probably bought ten to twelve of these, some brand new some with 100.000 mile on them. The fan blower never worked not even on low . I then realized once i put it on A/C . The engine idle does not slow or decrease idle like my other express van. ok i figured must be a fuse. So i changed 4 fuses , the blower relay & the blower all brand new. reading some where i seen to check the 4th prong on the Hvac control . the 4th prong had 12.3 volts . So Today i went to junk yard and bought a hvac control panel out of the same year . figuring that must be it Again nothing is working. I took off and cleaned the ground cable G106 . again nothing . i been working on this for about a week or so and i cannot figure it out . Any help would be great. Thnak you for your help