73-87chevytrucks.com
73-87 Chevy _ GMC Trucks => 73-87 Chevy & GMC Trucks => Topic started by: Streetrod00 on May 10, 2015, 03:25:56 pm
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Hi folks, newbie to this site but not oldies; trying to get a handle on '74 Cheyenne Super vac HVAC operation in advance of charging the A/C. When I cycle through the various settings, all seem fine but A/C and vent. When A/C is selected, vent door on passenger side opens and air blows through front dash openings. When vent is selected, door on passenger side does not open. Is this correct (perhaps a re-circ) or is one of the vac lines mis-routed on control? New to these any any suggestions helpful. Truck is a factory 454 w TH 400 if helps. Thx - PM
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(http://s5d3.turboimagehost.com/t1/23104183_1.jpg) (http://www.turboimagehost.com/p/23104183/1.jpg.html)
(http://s5d3.turboimagehost.com/t1/23104185_3.jpg) (http://www.turboimagehost.com/p/23104185/3.jpg.html)
(http://s5d3.turboimagehost.com/t1/23104186_with_chart.jpg) (http://www.turboimagehost.com/p/23104186/with_chart.jpg.html)
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When A/C is selected and temp lever is full cold this is max recirc A/C and that door should be open. It's not labeled max like the later years I think starting in 76 or so.
Any other selection and that door will close.
Also when in max cold A/C recirc the blower should be on high if it is in its original configuration with the proper blower switch and vac controls via a single orange wire to to the blower switch.
Again that if all the correct parts are there and function correctly.
If you want control of the blower speeds in max A/C recirc disconnect the Orange wire from the switch.
That's how I have mine and have control of blower speeds at all times.
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Thanks for the help!