Vacuum for ac/heater blend doors

[DoubleL]

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]

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]

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]

I added the reserve ball to mine (1 port, teed into the purple between the engine and firewall), and didn't notice any difference; the vents worked either way.

 

[DoubleL]

Do either of you have a picture available?

 

[fleming442]

here ya go

 

[DoubleL]

View attachment 103480
here ya go

Thanks!!

 

[DoubleL]

View attachment 103480
here ya go

Should there be 2 vacuum lines from the firewall? Seems like I remember seeing a purple line but after the engine install, I only see a tan line from the passenger side of the firewall to the engine compartment.

 

[fleming442]

2 for an AC car, 1 if heat only.

 

[pagrunt]

2 for an AC car, 1 if heat only.

My heat only module don't have any vacuum lines. Everything is cable operated.