I have lots of heat on my feet, but it won't go to defrost, knob bounces back. Is it a vacuum line or a cable control? I saw a previous post that claims it a cable control that is bent, and you can straighten it out. Others, have told me it is a vacuum line. Thanks, Lynn
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The selection door, is operated by 1/4" vacuum hoses. When turning the knob or sliding a lever, to select between floor, vents, or dash deck for windshield defrost, vacuum is created by the valve body and the blower will then blow thru the desired vents. When these hoses/lines are compromised, especially on a vehicle over 15 years old it seems likely, vacuum won't be created, and the last working position, is normally where it stays! Until the lines are replaced.
I had the same problem. Fixed it by changing the climate control knob assembly on the dash. I was able to get a brand new one still in the box on ebay. Cost $150.00 the 1995 will not interchange with any other year even though others look similar the back is different. New they wil run into the $300.00 range. You get all knobs and switches including the push buttons for the AC. These units require a gentle touch easy to break. Good luck.
It sounds like vacuum is not getting to the vent, heat and A/C controls. Find the vacuum can. It may be under the hood on one of the inner fenders. The "one-way" check valve is usually located in the line and close to the can, make sure it works properly. The valve could be the very thing that's causing the problem. Trace the lines back to the vacuum block at the intake manifold or fire-wall, and also back to where the line goes thru the fire-wall. Check the can for leaks or obvious holes. They used to be just a plain metal can, but it could be a plastic ball. Check the lines as you go, for breaks and rub-thru's. Move the controls thru all settings and listen for vent door movement. Worst case is a bad vacuum motor or air flow position selector switch, and/or a faulty Blend Door Actuator. If you have been driving around with the Temperature knob or control set at the same spot for months, move it from fully cold to fully hot several times and wait for the air temperature to change each time. This will help reset the blend door and vacuum control system. Hope this helps... Let me know what you find.
Hi: On the back of the heater control unit are vacuum lines, make sure
plug is firmly attached. FIRST though check if vehicle does not go into 4WD high. If not then you
probably have a vacuum problem under the hood as vacuum controls heater, 4WD and
other functions. Check to make sure vacuum lines under the hood are
all attached starting with the vacuum pod (located in front L fender by brake module.) and chasing them under the
hood. If you have vacuum then check heater control module and lastly heater door vacuum actuators. Hope this helps.
There is a vacuum line that operates your selector switch, it is located under the hood, roughly in the center, up against the fire wall. If the line has leaks, your selector switch will not work and therefore all your blower doors will stay shut. Replace the line.
I did not have defroster or venting to the feet. All I had was vent. I brought it to the shop they replaced the mode door actuator which flips the doors inside to make it flow to the defrost or vent etc; This cost me $210.00. They had to take the dash apart plus disengage the air bag under the steering wheel to get to the actuator.