For a 1999 Chevy / Chevrolet Suburan 2500 with rear defrost, but applies to many other applications. Well, I got sick and tired of the A/C fan not working. I'm done. I'm pissed. Anyone else have the problem? The fan speeds start to work intermittently and then not at all, or they are all messed up? I was. Here's the story: When I purchased the truck the fan speeds did not work. It only worked on #4 speed (high) but in none other. Moreover, the button for the rear defrost was...well...not there. Apparently someone had replaced the Climate Control Module for the front of the truck with one that didn't have the controls for the read defrost, so I knew the controller wasn't the original. I set about purchasing the right one and installed it. Everything worked great. For a year. Some time after the fan speeds started not to work correctly again. I came to not be able to turn the fan off at all...then once I got it turned off it wouldn't come back on, or wouldn't come on at the right speed, etc etc. Now, it just quit working. So, with nothing to lose, I took the son of a-...the... I took the controller out and inspected it. I hope someone finds this helpful for whatever reason. I know I did. First, the module was taken out. This is the one I am speaking of, with the rear defrost button. If yours doesn't have it it is essentially the same controller, with a plug that plugs into nothing in the rear of it. Looking at the back of it, the rectangular plug is the one that is the fan speed control. It is a component that is separate all it's own, held in with a screw/bolt. Remove the screw to take the plastic bracket off, holding the component. Then it's just a matter of prying the four pins holding it down to pop out the switch's main core. Now, it's just a matter of taking this little black cylinder of annoyance and throwing it at the parts guy behind the counter at the nearest GM dealership. ---------- Post added at 09:59 PM ---------- Previous post was at 09:50 PM ---------- Ok, no, not really. But it's what I feel like doing. This is what the little bugger looks like. The little peg fits into the control knob at the front of the controller I pried the casing apart. There are just three tabs holding the two plastic parts together, wherein I found the insides only have 3 parts. A cylinder that fits inside the front half of the casing, a spring, and a metal plate. On the right are the contacts that are attached to the back, where the wires for the fan speed get plugged in. the problem lies with the cylinder inside the front part. I know it's a little difficult to see but there is a middle spindle that has a "T" on the end. This T fits into the slots of the metal disk you see. As you turn the knob on the front of the controller this turns the little spindle here, which turns the metal plate against the contact points, which select either OFF, 1, 2, 3, or 4. The problem is that the "T" is made of plastic. Plastic pushing a metal plate side to side. So, as you'd expect, the plastic wears down and then stops turning the metal adequately. So.....your fan speed stops working. Mine got stripped down enough that it then stopped moving the metal plate altogether. Sooooooo....now I'm stuck buying a whole new climate controller module, I don't believe I can just purchase the selector switch itself. I'll be headed to the dealership tomorrow to check and see. My guess is I'll have to purchase a whole new controller. Fun. ---------- Post added at 10:14 PM ---------- Previous post was at 09:59 PM ---------- My thinking was to do away with the original part and do something different. I think I may still do it. If I can find a 5 position switch of some type, I'll somehow make it work with this setup. It just seems like a waste to go ahead and get a replacement if it's just going to fail again at some point in the future because, in my opinion, it is a poorly designed part. With the help of a multimeter and a jumper wire I learned how the plug works and which wire does what. In the above photo: Slot #1 - Ground Slot #2 - Off position (necessary because it turns off the lights, turns off the A/C) Slot #3 - Switch position 1 (low) Slot #4 - Switch position 2 Slot #5 - Switch position 3 Slot #6 - Switch position 4 (high) As an aside.....there are two other plugs there. The small 4 wire plug is for the rear defrost. If your particular vehicle doesn't have (but can come with) rear defrost you'll find this plug inserted into a blank. The other, long, plug is for the lights, A/C on&off, zone selection, and temperature section. Lastly, if you have burned out bulbs for any part of your controller, it's a simple fix. Find the bulb that you think is the suspect one, turn it (counterclockwise) a 1/4 turn and pull it out. The bulb will pull right out the holder. Replace the bulb and pop it back in. So...!..that's about it. Just thought I'd share my finding with y'all! Hopefully, like I said, this will be helpful to someone. Or at least help you understand out the CCModule works. UPDATE So, I went to the dealership and, indeed, they DID[/] have the part! $30 later and yet another pull of the dash front and I'm back in business. If the dealership had it I'm guessing the part can be had somewhere else for less money.