AC Controls Fan not working on Hi

[HoffmansHaven]

I have a 1997 K1500. When you turn the fan to Hi it stops. It works in Lo, 2, and 3 but as soon as you hit Hi it just stops. Here is what I did. I tested everything and checked fuses. Didn't really find anything so I went to the parts store and bought new everything except the control. New fan, relay, resister and put all that in and still the same thing. I then took out the control and I noticed when I took one of the plugs off there is nothing for it to "plug" to. The controls in my truck were replaced at some point. Part number on it says 09378815. It was manufactured in Mexico on 9Apr of 2018. It didn't come in the truck. I wonder if it's the correct one for this truck. There are 3 harnesses that plug onto it. There is a large one with 6 wires and a ground it's rectangular and goes into the big connector towards the center. There is another long skinny plug that connects on the side. Lastly there is a smaller one on the other side with a smaller 4 pin connector. That's the one just going onto a piece of plastic. There's no metal tabs or anything that plugs into it. I think that's my problem. That smaller 4 pin has the purple wire that goes down to the fan on it too. I have no idea how this thing is even working. Has anyone ever examined these to any detail. Why would mine be like this? I noticed that on the long skinny connector it is just connecting to a ribbon on there. I tried to look up inside that the white housing of the control to see the smaller connector I am talking about might be something like that but I can't see anything in there. Is there a way to take that apart to look inside without destroying it? I know this is a long winded post but I want to fix this someday. Does anyone know if there are any diagrams with enough detail that would show what that supposed to be? Thank you.

Picture added for clarity.

 

[AK49BWL]

That plug is for rear defrost, if there's nothing there you have no defrost or they replaced the module with the wrong one (missing the defrost button). Your fan has a different issue, loose ground maybe?

 

[HoffmansHaven]

Yeah my truck does not have a rear defrost. I guess it's back to the drawing board. I am probably not going to mess with it until the fall now. I appreciate you responding. Question though, is there a place where the complete wiring diagram is available? I mean for free? Otherwise I can purchase it. That should help me next time I dig into it.

 

[Das Hatt]

On this site, go to the engine subsection and there are free factory service manuals available to download

 

[HoffmansHaven]

On this site, go to the engine subsection and there are free factory service manuals available to download

Thank you! I never thought of that. I did a search and found some. I am hoping that the 1997 and 1998 are very close to each other.

 

[east302]

How does the blower switch connector look? If it’s melted or if the pins are loose, you can get flaky blower operation. Move it around a bit and see if it comes on in high. Else, here’s the wiring diagram for the blower - see where you’re missing voltage.

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[1998_K1500_Sub]

How does the blower switch connector look? If it’s melted or if the pins are loose, you can get flaky blower operation. Move it around a bit and see if it comes on in high. Else, here’s the wiring diagram for the blower - see where you’re missing voltage.

@HoffmansHaven, while you're at it, take a look at that relay that controls "high" operation. See if the relay's getting power as it should, and works as it should.

@east302, thanks for posting that wiring diagram.

 

[GoToGuy]

Why are you concerned about close. The 97 and 98 are both available, get the one for your year truck.

 

[HoffmansHaven]

How does the blower switch connector look? If it’s melted or if the pins are loose, you can get flaky blower operation. Move it around a bit and see if it comes on in high. Else, here’s the wiring diagram for the blower - see where you’re missing voltage.

You must be registered for see images attach

This is fantastic. Just what I needed. Thank you!

 

[HoffmansHaven]

Why are you concerned about close. The 97 and 98 are both available, get the one for your year truck.

Sorry I didn't see 1997. I saw 1995 and 1998. I figured since mine was manufactured in like August of '97 it would be very close. Maybe I just didn't see the 1997.