Heat and AC has a mind of its own...

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July 14th, 2023, 12:53 PM

#11

knight13

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Quote:

Originally Posted by tech2

the door actuators are vacuum controlled and if you have a vacuum leak the doors will change position when the engine vacuum is low...off idle.
do you hear a hissing sound when the engine is idling?=vac leak

Not hearing any hissing.

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July 14th, 2023, 4:06 PM

#12

mountainmanjoe

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The HVAC system needs to be able to hold a vacuum even when there's positive pressure in the engine intake.
Shut off the engine and wait a few minutes. Then test if there's still vacuum on the source line.

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July 18th, 2023, 5:50 PM

#13

knight13

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Anyone have a source for a safe place to purchase a service manual so I can dig into this a bit more? Tried the normal Google search for a vacuum diagram and not have any luck yet. eBay only shows me a service manual for over $300...

I'm planning on spending a bit of time with it this weekend to see what I can uncover.

Ed

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