i also took notice of the modes when i was driving, in park the ac also came out of the defroster along with vents. when i started driving it only came out of the four vents. tryna give you as much info as possible to see if this is normal or if not something else to test. ive been using the original hvac controller, and am planning to ship the new one back since that one seemed worse than my old one

 

Air distribution should not change while driving. If it does, I would suspect a bad check valve under the hood. Looks similar to this and should be near the power brake booster: http://i.tfcdn.com/img2/A7tKhVkADcnL...AI*/fvUG-v8A.B You can check it with the vacuum pump. Cork off the black end, and one of the whites. Apply vacuum to the other white and it must hold vacuum. Auto parts stores have them in stock, usually under $5.

 

check valve passed, held vacuum for well over 30 minutes until i unplugged the hand vacuum

 

Crap, I told you wrong, sorry. Gotta leave the black end open, cork one of the whites and apply vacuum to the other white. At least you don't have to disassemble the dash again

 

as many times ive taken the dash apart it takes 2 minutes haha. so i checked it the new way you just told me leaving the black open and corking one white and feeding vacuum through the other white. no leaks...stayed at 20 for over 25 minutes until i released vacuum pressure

 

Mode switch on BLEND, (feet & windshield). With everything connected, remove the vacuum line from the black side of the check valve. Connect the vacuum pump to the black side of the check valve and apply 20". Should hold vacuum.

 

Vacuum did not hold during this test....was slowly dropping...does that mean bad check valve? If so what's the part number on it

 

On the white side of the check valve there are two vacuum lines. One goes to the 4WD, and the other tees to the vacuum reservoir and HVAC. Unplug each one and apply vacuum to them, (seperately). Post the results.

 

The one white side of the check valve goes only to the vacuum reservoir (to the right straighy across from the black side of check valve)....and the down white part of the check valve has 4wd and hvac on it...i can take a pic if it helps

 

line that runs to vacuum reservoir is fine...no leaks...the line that has hvac and 4wd did leak....about 10 after 10 minutes