1983 chevy sportvan 5.0..on firewall 2 12v/vacuum solenoids (they match) any idea of purpose? not hooked up needed? thank you!!

One of these links should take you to a page containing a schematic showing the routing of the vacuum hoses. Need pictured vacuum diagram for 1983 oldsmobile 307, 5.0 - Fixya

Chevrolet Vacuum Line Diagrams / Chevrolet Blazer And Gmc Jimmy 1969 1982 Vacuum Diagrams Repair Guide Autozone : 305 v8 engine diagram best wiring library 1997 chevy 305 engine diagram vacuum line picsdiagram for 305 w qjet. (scoobydoomemes.blogspot.com)

https://www.youtube.com/watch?v=34WJXJMNtfY https://www.youtube.com/watch?v=PErhl_mIwGA

see the diagram and fuse or c.breaker, test it and replace, see any wires connector loose or dirty with oxide. you must disconnect the positive side battery to make any test or inspection

My 1984 G30 Diesel has two filters. One is under the van below the side door on the passenger side. The other is under the engine cover inside the Van mounted to the engine itself it is rectangular.

i dont think your car has the type of cumputer that there talking about

chevys firing order is 1-8-4-3-6-5-7-2- at front of engine number one cylinder is on drivers side

You should have a 4l60E in your astro van. Which is electrically controlled, so no vacuum modulator. However, to address the ventilation selector not working... look for a vacuum line exiting the firewall and going to the passenger rear of the intake manifold. You will likely find it broken or disconnected there.

the 10gauge purple wire on the solenoid should be HOT when starting. could be ignition switch or neutral saftey switch.

not sure if this helps but have a read on this

page.http://www.2carpros.com/forum/1979-chevy-van-1979-chevy-van-nuetral-safety-switch-locatio-vt135072.html