Yes, it might be hard to find such a diagram. Short of a factory service manual, I don't know. Perhaps a friendly parts person at a Chrysler dealership might be able to provide you a copy of how the vacuum lines connect, and how routed.
What you generally have is a single vacuum line from the engine going into the firewall and under the dash to the rear of the heater/AC control assembly. The line enters a fixture that can distribute vacuum signals through several hoses. One of those is the hose to the water valve, the only vacuum line that goes back into the engine bay. Selecting heat on the control obviously will send vacuum from the fixture to the water valve. The other hoses or lines connect to diaphragm operated door levers to control where air is sent.
See where the vacuum line for the valve goes back into the firewall. Then get on the inside and try to find that line-it may have broken or come apart. You may need to pull the heater control assembly out to get to the podlike fixture that the vacuum lines sprout from.
An alternative in this frigid weather, a make-do temporary fix, is to tee off a manifold vacuum line from the engine, and run a hose to the water valve. It will be on constantly, but it's winter, hey?
Dec 10, 2013 |
1991 Dodge Grand Caravan