수리 사례

2026. 6. 30. 작업

증상

My vents randomly switch between face / windshield... how do I fix this?

처리 내용

The blend air doors on the Windstar are vacuum controlled. The default position is defrost (windshield vents), meaning that if you loose vacuum supply it changes to defrost position. Look for a vacuum hose going through the firewall and trace it to where it hooks up to the intake manifold. It goes through a one way check valve and it teed into a vacuum canister. Do a visual inspection on all the vacuum hoses connecting the items above, looking for holes etc. You also might have a pinhole in the diaphragm in one of the actuators. A vacuum pump like this one pictured below can be helpful in finding the problem. You don't really need all accessories, a standard mityvac can be bought for around $30. I am not sure about the cracking, but the AC blowing on a hot windshield should not damage it. Is it possible the cracking noise is coming from under the hood? Below is a diagram of the vacuum harness, to give you an idea of how the system works. Most of this is under the dash, except for the v