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AC Changes on Acceleration


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I am about 80% sure that my AC vent position is changing on acceleration. When I let off the gas the AC upper vents come back strong again.. It doesn't seem to happen everytime.

I know this subject has been covered before and it has something to do with a vacuum check-valve but I did a search and couldn't find it.. Anyone experience this and what's the fix, Thanks, Mike

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Find the vacuum line feed to the HVAC where it goes thru the firewall. Inside the engine compartment it should be fed off of a vaccum reservour that is fed by engine vacuum with a one way check valve. It sounds like the check valve is leaking/failed or the reservoir is not holding the vacuum so that you loose vacuum to the HVAC under load when the vacuum goes low at heavy throttle. I think the vaccum reservoir is under the battery tray but I am not sure. Just follow the vacuum lines and you should find the check valve the the tee to the HVAC feed that would/should be between the reservoir and the check valve.

thanks Guru, the vacuum reservour is behind my pass side bumper I posted a photo below. Since its intermittant right now I can imagine that the check valve is beginning to fail.. I will seek it out and replace it... Thanks for the help, Mike


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