Grand Cherokee AC air door issue
 

I own a 1994 Grand Cherokee and the AC air mixture door sticks sometimes
and will mix hot and cold air for a few moments, then I hear a
light thump and the door closes and cold air comes out the vents.

I think the linkage that controls the door is sticking and it is dirty
with debris around the linkage. Where is the linkage control located on
the Grand Cherokee and what does it look like ? The underside where the
floor vents is where the door is located, but I cannot se the linage like
I could on older autos.

I see a small bell shaped cylinder with a line going into it, but I'm not
sure what is is. The part in under the drivers side near the center where
vents branch out from main duct.
Any help would be appreciated.
Thanks.

WB

WildBill66 did pass the time by typing:
> I own a 1994 Grand Cherokee and the AC air mixture door sticks sometimes
> and will mix hot and cold air for a few moments, then I hear a
> light thump and the door closes and cold air comes out the vents.

Sometimes the sealing foam tape they use comes loose and gets in the
way of the door, or the vac motor gets obstructed either by dirt or
by a wire bundle coming loose and resting on it. But more often than
not it's a vac leak on the engine side.

> I think the linkage that controls the door is sticking and it is dirty
> with debris around the linkage. Where is the linkage control located on
> the Grand Cherokee and what does it look like ? The underside where the
> floor vents is where the door is located, but I cannot se the linage like
> I could on older autos.

Like all things ZJ, they are hard to get at.

> I see a small bell shaped cylinder with a line going into it, but I'm not
> sure what is is. The part in under the drivers side near the center where
> vents branch out from main duct.

That's the heat/defrost door actuator

Here are the rest.

Recirc door air actuator.
This pain in the butt is located above the blower motor on the
firewall side of the HVAC unit.

Panel/defrost actuator.
Drivers side of the HVAC unit about in line with the VIC. Not sure
But I think you can get to it by taking the VIC out. It's been a while.

You might have a slight vacuum leak and it's taking that long for the
vac to build up and finish moving the door.

As old as your ZJ is, I'd be checking all the vac lines under the hood.

--
-- DougW -- 93 ZJ 4.0 http://members.cox.net/wilsond
HESCO Supercharger - 300W IASCA Stereo - Edelbrock IAS Shocks
Gibson Exhaust - rear DCpower - custom gauge install - Stillen Rotors
Banks Header - and BEER, in the fridge!

Doug,

I'll start with the vacuum leak check since its the least painfull back
breaking checks.

I replaced the AC blower fan in November, I should have pulled the seat
out, would have been easier with more room in the floor area.
So if no leaks are found. Do I pull the blower motor or do I have to pull
the glove box to reach
the Recirc door air actuator ? Is the linkage visable or do I have to
fell around to find it by hand ? Thanks.

WB

WildBill66 did pass the time by typing:
> Doug,
>
> I'll start with the vacuum leak check since its the least painfull back
> breaking checks.
>
> I replaced the AC blower fan in November, I should have pulled the seat
> out, would have been easier with more room in the floor area.
> So if no leaks are found. Do I pull the blower motor or do I have to pull
> the glove box to reach
> the Recirc door air actuator ? Is the linkage visable or do I have to
> fell around to find it by hand ? Thanks.

Unfortuantly you can't get to it through the top since the relay tray hides
under the glove box. It's a reach around the back/side and is a real pain
in the butt as there is very little space. I think the big service book
states to remove the whole assembly for service. That's nuts since it
means discharging the AC system.

I service what I can reach and live with the rest. :/

As for breaking your back working under the dash, try this.
Get a piece of 1/2" plywood about 1' wide and 3' long. Sit
it on the door sill then lay down on top of it. that gives
your back a rest.

--
DougW