Tempermental blend door

[slickemhoundd]

I found 2 broken vacuum lines under the hood, one for the egr soleniod and one for the 4wd actuator. Abd it seems to coincidental that the blend door functions properly unless under acceleration. I repaired the actuator line but not egr. could these be related or should i look somewehere else. Oh and under acceleration it switches to defroster, when cruising or idle its where i have it set on climate control

 

[FIND]

You have a vacuum leak. Under acceleration, engine vacuum drops, so you lose things that are on vacuum control unless you have a good reserve of vacuum. Your blend door runs on vacuum. Defrost is it's neutral position, it needs vacuum to reach any other position.

If you are having trouble finding the leak, a little carb cleaner sprayed around will find it for you. Once a leaky line sucks up the carb cleaner, your idle will change a noticeable amount.

Edit: Just noticed that you said you haven't replaced the other bad vacuum line. Looks like you found your leak. Fix it and everything should work fine. If not, look for more leaks.

 

[bobflood]

Also, the climate control vacuum runs thru a vacuum reservoir to prevent the air flow from changing every time you accelerate. The vacuum reservior is a black sphere in the passenger front wheel well underneath the inner fender liner. There is a "source" vacuum line that comes off the intake manifold into the sphere. Then a second vacuum line runs from the sphere up to the firewall, thru a connector, and into the back of the climate control unit. There is a check valve, I believe built into the sphere, that holds the vacuum when you accelerate and the source intake vacuum drops. Because the climate controls work properly except for the change when accelerating, I expect that you will find the check valve to have failed.

Good luck!!

 

[slickemhoundd]

Much appriciated help fellas. Time to dig in again. I was hoping to find direct replacments for the egr lines but seems as if ill have to adapt them together