Sittiing at a light today my heater fan just quit. My AC light (on the push button switch) went off as well. However, with the fan on full (Loud), it will come on as well as the AC and all is normal. But only on the high position which is loud (normal though). If I turn the **** one click less everything shuts off. The AC/heater/fan will only work on high. Has anyone had similar issues. Truck has only 40,000 miles and is an 07 1500QC with the 4.7?
Thanks!

 

Your blower motor resistor has gone bad. I believe it's located near the blower up under the dash. Easy enough and cheap enough to fix. The resistor Limits current which is how you get lower speeds. When it goes bad, you only have full speedwhich is essentially bypassing the resistor.

 

Thanks!!