A/C switches to defrost under engine load. Little different than the usual.

[IBrokeDadsCar]

Hi all. I have a 2008 AWD V8 Limited Edition Explorer. Upon engine load, my A/C changes from the face vents to the defrost vents. I read all over this forum about how that's normally the vacuum reservoir. I just had mine replaced, and the new one seems to be holding air just fine. I also checked under the hood and didn't notice any cracked vacuum lines. However, after turning off the car I do notice what sounds like a sucking sound coming from somewhere around the intake plenum. Have we any documented newer explorers like this that had a similar issue and fix?

 

[camphead]

a/c issue

Just fixed same A/C issue on my 07 Exp. Checked vac lines running to A/C looked good. Put vac pump on line running to control switch in the dash,worked fine and held vac. Checked the check valve that is in that line under hood. It held vac when it should, but seemed not to react fast enough??
What the heck, went to Ford and spent $14.92 and fixed it!! The part # for the 07 Explorer is YG-360 (on the valve) The new Ford # is XR3Z-19A563-AA.
It was the answer for me