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Discussion Starter · #1 ·

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Discussion Starter · #3 ·
GenII, I'll look up GenI and make one up
 

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Thanks! My alt and compressor are on opposite sides, heater control valve in a way different place (and it has a very different function).

But I like all the purty colors.. :D

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Discussion Starter · #5 ·
Wait, isn't GenI cable operated :confused:
 

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Jasen said:
Wait, isn't GenI cable operated :confused:
Not my 89. Heater AC box doors and baffles are vacuum. Heater control valve (the plastic tree) is present and vacuum opereated BUT in my year, it doesn't control flow of water to the front heater core. It only allows hot water to flow or not flow to the rear compartment heater core. Hot water (in the stock arrangement) is always flowing to the heater box.

But I still like the purty colors.

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Discussion Starter · #8 ·
The diagrams I found for 89-90 aren't as nice and clear cut as the other, but I'll sort it out.
What colors would you like me to use.
 

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I had this problem, fixed it with vacuum hose. I ran mine straight up along the cowl to prevent heat ruining the hose just my :2:
 

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Discussion Starter · #10 ·
Lumpy, I've googled my brains to mush today. I've have tried every search criteria I could think of and some I couldn't think of. I would think the system works about the same as a GenII, but I can't find anything on how/where the vac lines run. This is probably the clearest thing I've found, but the banana head left out the water control valve vacuum circuit.

Image uploading. Refresh page to view
 

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That's the thing. There is no water control valve in my 89. Just for the rear heat. The one that goes bad for everyone else isn't present in mine. In stock condition, hot water circulates through the box all the time, even when you're calling for A/C.

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Discussion Starter · #12 ·
Yea, the rear vacuum actuated water control valve, or water on/off valve. I can't find squat on it other then it exists. If I could find out where the vac lines run to from I could put something together.

From the 2,543 crappy pictures and diagrams I looked at today I would glean that it is basically the same set up as a GenII, but is just an on/off set up.
 

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Jasen said:
From the 2,543 crappy pictures and diagrams I looked at today I would glean that it is basically the same set up as a GenII, but is just an on/off set up.
Nice of you to make your eyes bleed, looking at all those pics, just for me to tell you mine's working fine... :eek:

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Discussion Starter · #14 ·
Anything for you Lumpmeister :mrgreen:

If you'd ( or any GenI owner) give me a couple three pics of this goes here and then over there, I'd put something together for those people who's HVAC isn't working.
 

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Jasen said:
If your not getting heat, your vents aren't working as the should or you have no air flow for front and or rear heat, start here.
This is why I like the internet!

I would never have found the source of my problem without this. After much cussing and almost yoga-like contortion of my hands, I was able to connect a hose to what was left of the plastic straw in front of the throttle body. (I just didn't have the time or inclination to tear open my dash and remove the dog house.) I also replaced most of the other tubing and now my air changes direction as intended. It drives me nuts that GM engineers came up with this kooky scheme of tubes and valves in the first place. I guess it's not unique to GM, but still...

Now, I'm off to find out why my compressor remains comatose...
 

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Discussion Starter · #17 ·
Theres a vacuum junction under the dash on the pass side . If you pull the dog house you can get it.
 

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Then next is the control unit itself.
 

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The vacuum junction must be that round thing with a pin and spring on it ?
I've pushed in and pulled out but does nothing. Maybe it is the controls. It's hot here.
 

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No, it's a flat thing with 4 different-colored vacuum lines running to and from it.On the passenger side of the doghouse (you have to remove the center console but not the doghouse to see/get to it).
 
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