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Old August 28th, 2007, 05:02 PM   #1
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Default HVAC switches to defrost under load.

Here's my other issue on my truck ('01 Dodge Ram 4x4).

Say I have the A/C pointing at my face. If I'm on the freeway and give it 3/4 throttle so the load increases on the engine, the vacuum change causes my HVAC to switch to defrost.

I've checked with tech manuals and it is supposedly a common problem says to replace both check valves on the vac lines near the intake manifold.

I pulled both valves and checked them and they hold vacuum. The lines don't seem to have any leaks either.

Any help?
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