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International Automotive Technicians Network
Re: Vacuum On Hvac
Posted to Technical Discussion Forum on 1/3/2019

As memory serves me, on vac operated HVAC switches, you should have manifold vac. The check valve shuts so when manifold vac changes, you still have an accumulated vac source so your blend and mode doors don't change with engine rpm change.

Check the check v... Login to read more.