[Clint.steward]

Hello, sorry if this is in the wrong place...

The last couple months my cabin fan has been working intermittently, I have checked the resistor and connections/cable harness and they look fine as best as I can tell. The fuse looks fine as well.

All 4 fan speeds stop working sometimes, doesn't seem dependent on temperature, and it doesn't seem to matter if its been sitting awhile or not.

I think its the switch, I took the entire fan-controller module out and inspected everything for burnt it loose connections but it all looked fine as well.

Additionally when my fan speed dial isn't working, it doesn't turn the orange AC light off like it normally does. When it works the AC light and compressor will turn off when the fan is set to "0"

Any other recommendations before I drop +100 on a new fan controller module to replace the one switch?



I have a 2004 Colorado, regular cab, 3.5l 5cyl-auto

 

[OldGuy]

You have a ground problem. The ground for the blower motor is part of the notoriously bad "ground pack" on the passenger's side fender. Right by the breather box is a 10mm headed bolt that connects a little black plastic box with about a dozen black wires to the top of the inner fender. The bolt itself sometimes works itself loose, but usually you have to open up that little black plastic box and clean all the connections inside. That and the one on the other side next to the ABS actuator are known to be the source of all sorts of electrical problems with out trucks. You can clean up the stuff inside the little boxes, sand the fender down a little to create a good grounding surface and this will buy you a little time. The ultimate fix is to cut those little black boxes off and put ring terminals on all the wires - some of the smaller ones you can put 2 in a single ring terminal - and then put all those ring terminals between a couple of washers and them bolt them down. Pretty much everyone here has had to address those two little bastards at one time or another. They cause tail light problems, gauge problems, computer problems and all sorts of other problems.
I think you'll find this to be the solution to this problem and many of us have found that our trucks actually idle smoother and run better after taking care of these grounds.
Good luck!

 

[Clint.steward]

That also explains the "ABS fault" warning I've seen a few times in the last year or so.

Dashboard flashes that error then my stereo cuts power then resets it seems, I'm guessing its the same issue

 

[OldGuy]

Yep, you'll be surprised how many little problems you're having will be corrected when you cut those little pieces of crap off and ground those wires correctly. Do it today or the repair of the blower fan will end up getting worse requiring replacement of resistors, harnesses and all sorts of problems with wiring getting burnt and crusty. Get after it and enjoy your truck again.
Let me know how that turns out. I'm confident that it's all being caused by the ground issues.

 

[Clint.steward]

I took off that box and sanded the metal tab and the area where it attaches, but it turns out the wires in the pack are loose

I think I might go out later to take the whole thing out and put those rings on.

You just clipped those wire off the box? I don't need it at all?

 

[OldGuy]

You just found the source of all your electrical problems! Great work Sherlock! That little box is just a junction to connect all of those ground wires together. That's all it does, and it does it very poorly! Don't go super cheap on the ring terminals. You want this to be a permanent fix and not just a new problem. I wouldn't go to WallMart to buy the ring terminals, I'd go to a hardware store or an auto parts store. I'd buy the special pliers for crimping the ring terminals too. They usually come in a set with lots of connectors with the pliers. Again, don't get the cheapest set, go for the middle priced set. The crimping pliers will also have a wire stripper. Some of the smaller wires can be combined and put on the same ring terminal. I'd take the bolt out that holds that little box to the fender and get a couple of washers too, if you don't already have some. I'd sandwich all the ring terminals between 2 washers and tighten them down good. I'm sure that will take care of all of your electrical issues.
Let us know how that works!!

 

[reaver]

I d no idea this could cause an abs fault as well. I have that going on right now, so maybe I'll take a look at mine as well.

 

[firemedicss]

I had the exact same symptoms with my fan and also the radio. Cleaning the ground block helped for a short period of time, but about 2 weeks later, the fan motor died. Once the fan motor was replaced, no more issues.

 

[raterr]

I also had this problem on my 2010 V8 Colorado, I fixed the ground issue on the passenger fender, blower still quit, changed the control head unit for HVAC system, blower still quit, installed new blower motor 3 months ago, seems to have fixed the issue. Hopefully for good.

 

[U406P]

You just found the source of all your electrical problems! Great work Sherlock! That little box is just a junction to connect all of those ground wires together. That's all it does, and it does it very poorly! Don't go super cheap on the ring terminals. You want this to be a permanent fix and not just a new problem. I wouldn't go to WallMart to buy the ring terminals, I'd go to a hardware store or an auto parts store. I'd buy the special pliers for crimping the ring terminals too. They usually come in a set with lots of connectors with the pliers. Again, don't get the cheapest set, go for the middle priced set. The crimping pliers will also have a wire stripper. Some of the smaller wires can be combined and put on the same ring terminal. I'd take the bolt out that holds that little box to the fender and get a couple of washers too, if you don't already have some. I'd sandwich all the ring terminals between 2 washers and tighten them down good. I'm sure that will take care of all of your electrical issues.
Let us know how that works!!

OldGuy is correct. Check out "Method 3" in this post: https://www.355nation.net/threads/how-to-hvac-fan-motor-resistor-connector-replacement.6401/