Trucks been stock on defrost or a while, with winter coming I feel like I should fix it now. So, just taking a quick peak, I saw



So, is this the problem or do I need to look some place else, and if it's not the problem, what does this go to?

 

Check around for a hose. Obvious that the controls aren't getting a vac.

 

What is that uncapped line for? Does your 4WD still work? Plug that open line off just above the booster with a vacuum rubber cap.

 

My dually did the same thing and I found the same fitting uncapped. Fold a piece of duct tape over that open fitting and see if things don't straighten out.

 

Mine looks like this......

 

I did a quick look and didn't see anything. I'll try capping it off, but I guess what I'm wondering is the missing line the ac control or is it for something else?

 

It's hard to tell from that pic. but at that junction there should be an input from the vacuum pump, and 3 output lines, one to the cruise control, one to the transfer case if you have 4 wheel drive and one to the hvac control if my memory serves correctly. will take a look at my truck in the am to make sure I'm correct.

 

Easy enough, before you cap anything, with the truck running, put your finger over the barb and see if you have any suction.

If not, then look down and you will find you vacuum supply line. You may have to track it back from the pump on the engine.

 

It's got vaccum, so that goes to something. I'll try to just cap it today amd hopefully that works.

 

The missing line probably goes to your cruise control. Located under the D/S battery. The cruise line also gets brittle and breaks, you may want to replace it.