Blend Door Actuator Not Moving

Hey guys, I have a 98 378 day cab. Truck started out not having heat, I removed the blend door actuator and it closed (by gravity), now I have heat! Now that temps are warming up in Wisconsin, I want a/c. So I figured it was time to replace the blend door actuator. After doing so, it still doesn't move when selecting hot to cold. The door moves freely by hand. Want to get your thoughts before I spend $350 and replace the entire "temperature control unit"

Thanks

 

Thank you for your response, I haven't done any diagnostic work yet. I'll check it out tomorrow, appreciate the offer on the control, I'll keep you posted.

 

There are 3 wires going to the actuator. Red, orange and black. With the actuator unplugged. I have solid voltage on the red, nothing on orange and low voltage on black, around 10v.

When I plug the actuator in, red stays at solid 13v (truck is running) orange has low voltage around 10 and black now has a solid 13v. Looking at a wiring diagram, I know red is my power, orange is my signal and black is my ground. Using my power probe, I applied a ground to the black wire while being plugged into the actuator. The actuator moved!

While continuing to hold ground to the black wire I rotated the hot/cold selector, one click in any direction causes the actuator to rotate completely, meaning it's not going to blend my air..... or is it? Any tips on where to look for the stray voltage on my ground wire or an explanation as to why the actuator only moves from one extreme to the next would be great.

Thanks!!

 

I traced the short or stray voltage down to this....... when I pull on it, I get a ground at the actuator, when I push I get stray voltage, while it's plugged in.

 

What this capacitor does is above my pay grade but I do see a wire broken off that will get soldered back on and hopefully fix the issue. I'll keep you posted.

 

Soldered it up and everything is back to normal, thanks Smellfunny for your responses and in put.