I have a 1995 Dodge Ram 1500. My air conditioner and heater work fine and blow cold and hot air good. I have a problem though. I can have the regular vents on to blow at your face, and anytime I accelerate a little or alot, all of the air automatically switches to the defrost vents by the windshield. When I let off of the accelerator, it switches back to the setting I have it at. Is this a vacuum leak? If so, do you have any idea where I could start to check for a leak? Thanks.
Also, my front end squeaks horribly. It squeaks when I turn the wheels and hit bumps. I hae been told this is simply bushings. What bushings would it be and how do dI go about changing them? Thanks for any help anyone may have.

 

there is a check valve in the vacuum lines going to your heater/ac controller that his bad. your vent default is to defrost so when there is no vacuum, air will blow out the defroster. when the valve is bad and you get into the throttle, your vacuum signal will drop and you will loose vacuum to the controller causing the flaps to go to defrost. easy fix, you will find the check valves in-line on a vacuum line going to the firewall above the passenger side head.

 

Do I just go into auto parts store and ask for vacuum line check valves?

 

I think those are a dealer item...

 

Thanks Steve. Also can you check my post above about my fron end squeaking? Can you offer any help on this? thanks.

 

the squeek could be anything from bushings to shocks & suspension parts that are w/o lubricant. i'd start by lubricating the bushings 1st, it is the easiest. you could also have someone bounce the front of the truck while your under it with a mechanics stethescope... put it on all the joints to listen for any squeeks...