ideling

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miesk5

96 Bronco 5.0
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yo 89.

Check the vacuum lines

and esp the Vacuum line to the Outside Recirculate Door Vacuum Motor on passenger side near firewall and hood hinge

here is a pic of it by Matt; https://www.supermotors.net/getfile/874153/fullsize/p1010014.jpg

Shiny piece in upper left

The air handling system is designed to provide defrost when no vacuum is applied to any of the three air door vacuum motors. This is done to prevent a situation where defrost cannot be obtained due to a system vacuum leak. Instead, a leak in the vacuum control circuit will send all airflow to the defroster outlets. This condition may occur during acceleration (slow leak), may exist at all times (large leak) and may happen only when certain specific functions are selected, indicating a leak in that portion of the circuit.

 

Seabronc

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Ditto what miesk5 said. A common place for a broken vacuum line that causes this problem is the black line that goes through the fire wall on the passenger side. Check it back to the vacuum reservoir and also the feed line to the reservoir, (generally RED).

Good luck,

peace.gif


 
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89xlt

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what is that small white hose to the left in that picture mine seeems to be chewed or broke in half

 

Rons beast

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That white hose is the vacuum line to the interior air recirculation door. If it is broken or chewed it is a good source of your problem, and could cause other drivability problems. It has to be repaired, ( replaced with a new hose).

 

Seabronc

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The color of the line may depend on what year the truck is. According to the 1989 and 1995 EVTMs the line is Black on the engine side of the fire wall and up to the Harness Vacuum Connection Block. In some vehicles it goes from the vacuum tree on the intake manifold to a Vacuum Reservoir on the right side of the engine compartment and then to the Harness Vacuum Connection. The reservoir is to prevent sudden drops in vacuum level, such as during heavy acceleration, from having a negative effect on the A/C Control. Diagram attached

Hope this helps.

Good luck,

peace.gif


1995 AC Vacuum.jpg

 

miesk5

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yo,

Altho I try not to refer to another site, look @ Vacuum Hose (Line) Replacement w/Rubber Hose in an 89 F 1505.0; (almost 100% same as Bronco"...This should cover most 87-96 V8s (302\351); for the I6s (300)s the solenoids are in the same general area, as well as the valves. You can use this article as a basis to replace yours, just keep in mind it..."

Source: by Booba5185 (Matt)

--

to add to Seabronc's info on colors; altho Vac Line Colors don't match on on older vehicles due to changes over the years; & same for the electrical wiring too.

HVAC in 92-96;

Black = from engine source to vacuum check valve & to vacuum reservoir tank & to Control Panel;

White = actuates the Outside Recirculate Door Vacuum Motor;

Blue = Mix (actuates the FLOOR/PANEL air door two-position vacuum control motor);

Red = Floor Flow & Yellow = Panel, (actuate the FLOOR/DEFROST three-position air vacuum control motor).

READ MORE

 
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89xlt

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when its cold or i first crank it up it will some time reach 2000 rms til it warms up.

 

Seabronc

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It is normal for the engine to have a high idle when you first start it especially in cold weather. If it drops back to normal idle when it warms up, I wouldn't worry about it.

Good luck,

peace.gif


 

miesk5

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yo,

a vacuum leak will cause a fast idle speed; A rough idle or stalling; Hesitation or misfiring when accelerating; & can cause a sensor to turn on the check engine light and have the EEC store a code

 

miesk5

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yo,

I think you should combine a few of you posts into one since there are other issues that may help us here figure out what to dwell on first;

such as in your;

"everything blowing on defrost very little on floor. HELP" at;

"http://broncozone.com/topic/22423-everything-blowing-on-defrost-very-little-on-floor-help/page__p__117050#entry117050

Our responses centered on a vacuum leak at a few HVAC points and other places in Emission and brake booster sys

I replied a few mins ago with your Q about what a vac leak would cause w/;

yo, a vacuum leak will cause a fast idle speed; A rough idle or stalling; Hesitation or misfiring when accelerating; & can cause a sensor to turn on the check engine light and have the EEC store a code

There may be other posts that can be included, but I can open only so many browsers now to check

EDIT; ok the other post is;

no acceleration

http://broncozone.com/topic/22463-no-acceleration/

 
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