Air Conditioning blend doors

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Air Conditioning blend doors


Post by ttp17 » 01 Aug 2018, 14:28

I have just finished restoring my 1968 Cougar, 302 cid/4bbl., with factory restored A/C. The blend doors for the the A/C move when I accelerate or decelerate. For example: With A/C on MAX, air blows through the dash vents normally. But if I accelerate like passing on the highway, the blend door(s) cycle and air comes through the heater vents. New vacuum canister. Good vacuum check-valve. New vacuum lines.

Any one have an idea on what's happening here?


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Re: Air Conditioning blend doors


Post by xr7g428 » 01 Aug 2018, 14:43

Bad vacuum check valve or vacuum leak. Minus vacuum, the motors return to the default position (heater or defrost).
Bill Basore, Editor / Publisher
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