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I have a 2000 Chevy Astro that only blows out the defroster vents

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It is a 90% chance the plastic vacuum line to the heater control from the engine has broken.
Remove the air filter housing and the rubber hose from the engine to the air filter housing.
Look for a small black plastic tube coming from the pass side fire wall going back across the engine to the drivers side middle of engine.
Look for a broken section and repair with small rubber tubing.
Once the engine is started.....vacuum is restored to the heater control....and it should work as new.

Posted on Sep 30, 2009


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when your car is in defrost it has an ac cycling it removes the moisture then sends the air over the heater core depending on how warm you set it you can feel warm or cold but the ac is always cycling...ridding the need a good ac tech it will be okay...its just expensive going into the heater core if needed...!

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2000 chevy astro van front a/c switch is out - don't push airout

As for the air only blowing out of the defrost, your problem is not the switch it will be a small vacuum line that runs from the top of the engine directly behind the a/c compressor to vacuum tank located on the passenger side of the engine compartment just to the right and forward of the engine block. It is a small black tube. Once you find the break, a splice connector costs about $.20 at the parts store.

As for the fan not blowing on all speeds. Sounds like a resistor located in the blower motor housing under the hood passenger side. I just replaced mine. Costs about $45 and fixed the problem. Although these do go out with age, sometimes they indicate excessive load from the blower motor itself. If it happens again, look at that.

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i suspect the vents are controlled by vacuum and are not opening due to a vacuum leak.


Sep 01, 2008 | 2000 Chevrolet Astro

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