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Vacuum problem related to heater control problem?

2K views 16 replies 6 participants last post by  Wekesa 
#1 · (Edited)
Where does this Vacuum Hose go? Related to heater control problem?

While diagnosing a problem with my heater control only blowing with the switch at 7 o'clock, I started checking the vacuum hoses. I stuck my head under the hood and heard a loud hissing.

I pulled lightly on a hose and it was clearly disconnected. It seemed to have been connected somewhere around the alternator and the engine, but I can not see in there well enough to find out exactly where.

Attached is a picture of the hose and the connections on it. Can someone describe to me where it goes?


I sort of circled up the hose so that you can see where it is connected to the engine and the disconnected part at the same time.

By the way, I think the previous owner put in a newer factory stereo and in the process loosened hoses connected to the air distribution switch. After fiddling with the switch through the radio hole, I now get constant air out of the dash regardless of the switch position and no air out of the floor vents. Any tips on this 7 o'clock problem would be appreciated. The control rod is connected properly. I'll be back at it tomorrow when the sun comes up.
 

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#3 ·
Yeah- it looks to me like someone tryed to get creative with the vacuum hoses and left you a bit of a puzzle.There should be a sticker with a diagram on the left fender well, just forward of the fuse-box. As for the the vacuum manifold at the vent-selector, those hoses are very firmly attached to a rubber manifold that clips to the back of the selector via two stout clips and a steel ring. the connection there is go or no-go. A bigger pic of the engine-bay may reveal more odditys. Good luck.
 
#4 ·
That looks like a valve there at the end, usually that is on the line going to the valve cover. Do you have one going to the valve cover? Should be a big hose and a little hose.
 
#5 ·
I too thought it went into the valve cover, but there are no open spots there. I'll check again when there is daylight.

I completely forgot there was a hose chart on the fender. I'll check it.

I also noticed that after awhile the car simply dies like it ran out of gas or something. So, I plugged up the loose end of the hose and that stops the car from dying.

Since I have no heat and no matter the setting on the switches I get a steady cool air flow (it's cold here), I'm guessing the hose feeds the vacuum for the air distribution system.
 
#6 ·
If you can't regulate the heat this is the heater valve, no vacuum on that, usually when someone tries to take out the dash then it pops off then when putting it back doesn't fit it

Remove the speaker grille on driver's side, you should see that arm, try and fit it where it goes
 
#7 ·
The rod seems to be connected when I looked in. When I turn the switch from hot to cold and back, the rod turns in my hand.

The vacuum hose on the fenders is of no use at all. It does not show have of the If anyone has a better schematic of the vacuum hoses please share it.

The car is a 1993 900 Turbo Convertible. I just picked it up this weekend but I have no picture yet. I haven't even washed it yet. I'm trying to fix all of the little bugs so I can drive it. I just unlocked the stereo and I'm glad to learn that it works just fine. No upgrade needed right away.
 
#8 · (Edited)
cant upload pictures pm with email address
 

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#10 ·
Great Pic!

That is a beautiful engine bay my friend! :p I'm inspired to clean mine as soon as I figure these hoses out.

But we are making some progress. The connection I'm focusing on is the one in the lower right quadrant of your photo. One hose comes up and over the coolant hose and then goes back into the car somewhere. That hose is fine.

The hose coming out of the bottom of the t-connection is my problem. In your photo it curls under the engine to the right of the oil cap and disappears. Where is it going? I'll be all sorted out if I can figure that out.

This give me hope that I can re-attach the hose myself if you were able to replace the hose with the blue silicone hoses.
 
#12 ·
Wekesa said:
The hose coming out of the bottom of the t-connection is my problem. In your photo it curls under the engine to the right of the oil cap and disappears. Where is it going? I'll be all sorted out if I can figure that out.

This give me hope that I can re-attach the hose myself if you were able to replace the hose with the blue silicone hoses.
You cant see it in the pic but that hose on my car ends up at the cruise control unit in the left fender,and the the boost gauge, pressure transducer and over boost switch in the dash.
 
#13 ·
I stopped by a "foreign" car repair place by my house today thinking the guys there could simply look at the vacuum hose and connector and be able to tell exactly where it went. I was wrong. They poked around for 5 minutes or so but were stumped.

Then one guy told me that the only way they can figure it out was to "smoke it out." If I understand correctly, that means blocking the air intake and then feeding smoke into the vacuum system. Wherever the smoke comes out is where the hose is missing.

Has anyone every heard of this?

I'll probably take it back to them next week so they can smoke it out.
 
#14 ·
Which vehicle are we talking about? I see a few in your profile. The original owner's manual should have diagrams of the vaccum layout, as well its often inside the engine on the fender. Even if you don't have the OM, one of us probably does.
 
#15 ·
I'm talking about the 1993 Turbo Convertible. And the next time I see one driving down the street, I'm going to ask the driver to pull over and pop the hood so I can inspect their hoses.

The fender diagram does not show all of the hoses. And neither does the manual. But they both helped me eliminate possibilities.
 
#16 ·
Yeah, I think someone did some messing around in your engine bay - likely to compensate for some other messing around which was compensating for some other string of misdiagnosis. Its a wonder our cars run at all sometimes when we get them.
 
#17 ·
The question is answered!

I spent the afternoon at the salvage yard. They had two 900 turbos there. On one all the vacuum hoses were gone. On the second one, the hoses were almost an exact match for my car.

So, I found out where the disconnected hose goes. It splices into the long hose that runs along the body just under the windshield wipers. One end of that hose runs to the vacuum canister.

When I got back to my car, I plugged it to the loose hoses I had not previously seen, and YES! Now the air distribution switch works perfectly and I can hear all of the servos working.

Now I'm searching the forum to find out why I still have no heat. It just blows cold or warm, but not hot. But it definitely blows. I'm just happy I'm figuring this stuff out.
 
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