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AC Outlets Change When Accelerating: Need to Confirm Part Number

Sand-Dog

NAXJA Forum User
'98 XJ, 4.0 engine. Searched the past threads. Checked / repaired vacuum line system in from the ball vacuum reservoir canister on the front bumper back. When accelerating, the AC/heater outlets will change from the front vents on the dash to the defrost vents. According to the search, it appears I need to change the vent door actuator. One thread lists the part for a '99 as p/n 04864995. I'm thinkin' it was the same part for '97-'01. Can anyone confirm? Any other ideas before I call the dealership on Monday to order the part?
 
According to my parts guide, your number is for the blend door. The defrost door is 04864994. However, I'm not sure what the real difference is. It's the same for 1997-2000. I didn't check the 2001.

Given it switch's under accel, I'd still suspect a leak somewhere or possibly an incorrect hookup to the reservoir. Since this is a low engine vacuum state, the reservoir should have enough to keep the ducts and cruise control working.

Just to make sure, do you have cruise? Is the reservoir a "ball" (as you said ) or a cylinder with ports on each end?
 
It's the ball reservoir, and I have gone through the vac line system which is made from a somewhat flexible pvc (?)...the vac lines...except for power brake booster... are not rubber, but the connectors are. I've replaced the connectors up to the firewall.
 
WIth the engine off, the blend door(s) should stay in some position. When you turn the dash knob, the blend door(s) 1should change position; you should hear a little hiss and the door(s) kind of 'thunk' into their new positon.
Now, I don't remember what position they are under vacuum in and what position the vacuum releases in, but, if you figure out which position is which, (say with the engine running perhaps), turn the car off and come back later and you dont hear the little 'hiss & thunk" when you turn the knob, I would suspect a vacuum leak and not a faulty door
 
Sand-Dog, Have you found a fix to your problem? I have the exact same problem with my 96. The air is still cold....it's just out of the defrost vents and not the front vents. I've taken some of the dash parts out to take a look but i've been unsuccessful.
 
Before all y'all get really deep into the dash, I'd recommend taking a second (or third) look at the vacuum lines between the vacuum ball and the HVAC controls. Of special interest is the section of line running near/under the battery as that's a VERY common leak area. Of course, leaks in any area of the vacuum line will result in the defrost vent problems described.

Jim www.yuccaman.com
 
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