Blazer A/C blows out defroster vent only

A factory service manual for this will show a diagram of the vacuum lines and their routing in the vehicle.

Ted

I have a 1995 Chevy Blazer, the A/C blows out the defroster vent only. I have read that the most likely cause is a leaky or loose vacuum hose. Where would these vacuum hoses be located?

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When the Defroster is on, AC airflow and heater airflow are both directed to the defroster vent. This is because the AC air is very dry and defrosting works faster.

Under normal (non-defrost) conditions, heat and AC airflow are directed to the dash vents or to the floor vents by means of Flapper valves in the ducts under the dash. Each Flapper is operated by a vacuum-powered Actuator.

Vacuum is provided by a hose from the engine to the climate control Selector. The Selector distributes the vacuum through other vacuum hoses to the Flapper Actuators to direct airflow.

Where there is airflow but it is not coming from the proper vents, it could be the result of (most probable first):

1.) A Flapper is stuck in one position by rust or distortion. 2.) A vacuum line from the Selector to an Actuator is leaking or disconnected. 3.) The link from an Actuator to a Flapper is broken or disconnected. 4.) The vacuum line from engine to Selector is leaking or disconnected. 5.) The vacuum distribution section of the Selector is bad. 6.) An Actuator is defective.

Sorry, this does not answer your original question as to where the vacuum lines are located. You will just have to get upside down under the dash with a flashlight and root around to find them. You can then also wiggle and free any stuck flappers.

Good luck.

John E. Ardans Bothell Washington ________________________________________________________

There is a round ball about 4-5" in diameter attached to the hood with vacuum hoses connected. One was loose and hanging between the engine and firewall. But I can't find where it connects. Getting closer, am I on the right track here?

Thanks

Found it... the loose hose plugged in behind the fuel injector, all works well now

Thanks for everyone's help