I have an 03 GMC 2500 HD Duramax with the electronic climate control. The climate control will change from heat to AC to defrost etc just fine. The problem is I have only one fan speed it seems...which is low. The digital read-out will say that it should be blowing high but its not. The fan also seems to keep running after the ignition is turned off. I did not notice this before the other problem started. Any ideas from the pros?

You have a failed "blower control module". You most likely will not have any melted connectors, just a failed module.

http://www.dieselplace.com/forum/showpost.php?p=3972639&postcount=2

Thank you Mccall. From your other posts thats kinda what I suspected. Is this hard to replace for a shade tree mechanic? I'd rather not go to the dealer with this if I can get out of it.

There is a listing on Ebay to ship the unit off for repair. Repair cost is $40 plus shipping. I just sent one off for repair. Will let you know how it turns out...

There is a listing on Ebay to ship the unit off for repair. Repair cost is $40 plus shipping. I just sent one off for repair. Will let you know how it turns out...
Which part are you talking of ???
I'm referring to the $90 89018778 "blower control module", which looks like this http://t2.gstatic.com/images?q=tbn:XhyC5HYudk3dmM: (http://www.google.com/imgres?imgurl=http://www.rmsautoparts.com/prodimages/89018778.jpg&imgrefurl=http://www.rmsautoparts.com/proddetail.php%3Fprod%3D15-80567%26cat%3D5&usg=__8h6EMUz56quyX8z7nGXxDGIEBgA=&h=326&w=500&sz=43&hl=en&start=4&sig2=9B4Rps_sRDmW-zvp92qVog&zoom=1&um=1&itbs=1&tbnid=XhyC5HYudk3dmM:&tbnh=85&tbnw=130&prev=/images%3Fq%3D89018778%26um%3D1%26hl%3Den%26sa%3DN% 26rlz%3D1T4GWYE_enUS255US256%26tbs%3Disch:1%26prmd %3Divsfd&ei=WSYITeiUHoSKlweXvv3hDw)

Which can be easily extracted and swapped following the link in post #3 here http://www.dieselplace.com/forum/showthread.php?t=277135&highlight=blower+motor+connector
Or even just staring at the picture in post #7 there.

Thanks for the info Mccall. Mine went out yesterday and almost took it to the stealer. You will end up saving me the $45 for the mechanic to spend 5 mins troubleshooting. One more thing to do before the road trip on Saturday but at least my HVAC will work. :D

Thanks again, Problem solved. The part cost $130 from O'reilly auto parts and took maybe fifteen minutes to replace. Definitely cheaper than the stealer. : )