Help finding AC/heater vaccume diagram

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  • 3.9L
  • V6
  • 2WD
  • 174,000 MILES

I need some help on finding out where all the vaccume lines go on the box. When we pulled it out we forgot what went where. Is there a diagram of this?

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Thursday, October 23rd, 2014 AT 6:25 AM

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Are you referring to the heater box? If so, you need the manufacturer's service manual because there's going to be multiple variations, and you won't find this in Chilton's or Haynes manuals. Mopar manuals are easy to find on eBay and are pretty inexpensive.

Once you have that diagram, the hoses should be color-coded or have different color stripes on them. The alternative is to just hook them up in random order and see what works properly. You won't hurt anything when you get them wrong. The only time this is not an option is when the heater box has to be removed to access some of the vacuum motors. Your best bet in that case is to go by the lengths of the hoses. Obviously a 12" long hose can't go to a vacuum motor 24" away.

Another clue is to look for 3/4" long shiny spots on the hose that show where it was clamped in a metal retaining clip, or a 1/4" long spot that shows where it was clipped in a plastic finger molded into the box. Often a hose will take a set and have a curve in it where it went around a corner.

One thing you should not go by is the position of the hoses in the connector on the back of the control assembly. There's multiple slides in that unit, and each one has multiple holes that line up in different settings. The port for defrost, for example, will almost never be right inline with or behind the "defrost" button.

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Thursday, October 23rd, 2014 AT 11:43 PM

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