Yo M,
Yes it is cable operated.
http://www.chiltonlibrary.com/content/images/8492/images/84926015.gif
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"...Some of the later control panels with knobs have mostly cables behind them, and others use more vacuum. If you get a vacuum leak, you'll lose control, just like if a cable pops loose. It's pretty easy to pull the panel out a little & inspect behind it; & If you can pull your radio out, you can look at the top of the A/C controls. Sometimes a wire from the radio gets tangled in the mechanism, and it can lock it. Or, the cables that connect the slides to the blend doors can kink or come loose. It's most common for the cable to pop out AT the blend door lever, over the passenger footwell, but that never locks the control, so it's probably not what happened in yours...." by Steve
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Had issue downloading and copying this tab
It is available column document, so try and look at it in number order...
CLIMATE CONTROL—LACK OF HEATING OR Article No.
COOLING PERFORMANCE—NEW TEMPERATURE 91-19-10
DOOR CABLE ADJUSTMENT PROCEDURE—
VEHICLES BUILT FROM APRIL, 1991
• CLIMATE CONTROL—NEW TEMPERATURE DOOR
CABLE—REMOVAL, INSTALLATION AND
ADJUSTMENT PROCEDURES—VEHICLES BUILT
FROM APRIL, 1991
FORD: 1991 BRONCO, F SUPER DUTY, F-150-350 SERIES, F-47
ISSUE If the entire cable must be removed from the
A lack of heating or cooling performance may occur vehicle, proceed as follows:
because the new design temperature door is not
properly adjusted. The new design allows the cable 6. Disengage the cable wire from the temperature
to be preadjusted before installation at the assembly door crank.
plant. 7. Disengage the cable connector and wire from
ACTION the control assembly.
If service is required, refer to the following removal,
installation and adjustment procedures. INSTALLATION
REMOVAL 1. Attach the cable to the control head and the
wire coil to the temperature door crank arm. The adjustment clip is attached to a molded-in
bracket located in the upper left hand area of the 2. Align the adjustment clip with the opening in
heater core cover. The clip is retained by two tabs. the molded-in bracket as shown in Figure 1.
Special service tool (D91T-18532-A, Heater-A/C
Temperature Cable Clip Remover) or equivalent is 3. Push the clip firmly into place.
required to depress the locking tabs to allow a. Ensure that both tabs retain the clip to the removal from the attaching bracket. bracket. An audible click should be heard on
engagement.
1. Release the glove box to gain access to the
adjustment clip. b. Pull firmly on the clip to verify proper
retention of the clip.
2. Position the removal tool (D91T-18532-A) over
the bracket and clip as shown in Figure 1. ADJUSTMENT
3. Align the opening in the removal tool with the If the temperature door cable requires adjustment, retaining tabs, which project through the proceed as follows: bracket, and pull back firmly. This will depress
the locking tabs but will not disengage the clip
from the bracket. 1. Release the glove box to gain access to the
adjustment clip.
4. While maintaining the pull on the tool, pull the
clip away from the bracket with the other hand. 2. Pull back on the white lever of the adjustment
clip, Figure 2.
5. Examine the adjustment clip for damage during
3. With the tab held back... removal. If one or both tabs are broken or no
longer spread away from the body of the clip,
replace the clip (F1TZ-14A163-D).
PAGE 1
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Maybe temp blend door is jammed or loose & flopping around on its own. The easiest way to see it is to fully lower the glove box, pull the ~8 screws from the heater core cover, & look inside to the L (driver's side). You'll see the cable & control lever (in top L of 2nd pic) as soon as you fold the glovebox down, so inspect it first. The 3rd shows the whole cover - it's the large section in the top center with tiny white numbers inked near its bottom edge. The cables are visible, too.
http://www.supermotors.net/registry/media/72422
