My A/C works perfectly fine until I turn it to 4 or 5, then it just turns off. It used to work on 4 but I had to jiggle the **** to get it working now it completely stopped working. Could it be the whole control switch that I need to replace or is it some sort of relay / fuse? Thanks for your input. 06 Silverado 4.8L V8 crewcab in case you need that info.

 

I also have the 2006 4.8L, but in a standard cab. While it COULD be the blower speed ****, usually when that fails, all speeds don't work. When just 1 or 2 speeds stop working, that tends to be the blower resistor. The blower motor resistor (or blower control module), which typically sits on top of the air handler, and is located behind the glove box. I've had speed 4 (of 5) out on my 2006 Silverado for years, and have been too lazy to replace the resistor, but will soon, as I plan on selling it.

That said, typically the highest speed does NOT use the resistor, but with these newer vehicles, it might. The issue seems to be there are numerous options for our 2006 Silverados:

https://www.rockauto.com/en/catalog/...+resistor,6557

I *think* for the crew cab you want this one:

https://www.rockauto.com/en/moreinfo...SKGwT0iNB9crKP

 

So I removed and replaced my resistor and I still don't get 4 and 5 working. Could it still be the control switch or is it something more sinister?

 

When you say jiggling the **** made it work, that's where I would suspect the problem lies.

 

On my 1996 C1500, the blower switch is a separate item that clips to the back of the AC control panel in the dash, and can be bought at about any auto parts store. I am thinking on the 2006 Silverado that the switch is integrated into the climate control module. I've got the kind that has two temp sliders - one for driver and one for passenger, along with the mode switch, a few buttons, and the blower switch with speeds 1-5. I've not pulled it off, but do not see a separate switch part on rockauto.

I've got the wiring diagram bookmarked on my work computer, but not here. Maybe someone else can chime in with the link to the manual for a 2006 Silverado 1500?

 

That's exactly what I have in my truck. I'll buy that and see if it works. Thanks guys

 

I found the wiring diagram for the HVAC system on the 2006 Silverado with manual control:

HVAC Systems - Manual — 2006 Chevy Truck Silverado 1500 2WD V8-4.8L VIN V Service Manual | Operation CHARM

According to this, speeds 4 and 5 both go through the resistor module, which INCLUDES the relay. Since you replaced that, looks like the switch is the only thing left in the diagram...

EDIT: In my case, with just speed 4 not working, I'll probably start with the resistor/relay module first, and see if that fixes it.