Vacuum for ac/heater blend doors

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DoubleL

Not-quite-so-new-guy
Oct 4, 2018
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4
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I recently had 5.3 LS swapped into my 1985 El Camino. Had new AC compressor installed also. AC blows cold but only through the defrost vents. I found that the vacuum is not connected at the firewall under the hood. Can anyone tell me where and how to get the vacuum connected to get the blend doors to operate. I also noticed that the heater control valve probably should have vacuum to it also, correct? Thanks in advance.
 

fleming442

Captain Tenneal
Dec 26, 2013
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Purple vacuum line controls the vents- hook to manifold vacuum.
Gray/white line goes to the heater control valve on the small heater core line- shuts off flow to heater core during A/C operation.

The rubber selector in the vent control is notorious for selection problems. It is held by a small plastic rivet that deteriorates and breaks. It can be fixed by replacing with a small screw.
 

MrSony

Geezer
Nov 15, 2014
6,790
6,673
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Des Moines, Iowa
You need a 2 port vacuum reservoir. purple in one nipple vaacuum line from the other to manifold vacuum. plus or minus a check valve. white/grey line goes to the heater shutofff valve to shut off coolant flow from the heater core. idk if that will work anymore with your setup.
 

fleming442

Captain Tenneal
Dec 26, 2013
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1547145397830.png

here ya go
 
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