Heater controls not working..vacuum? [solved].

[Paul Alexander]

Hi Everyone. i thought i would post this to hopefully help fellow novices, as this forum has been very helpful for a novice like me.

whenever there were two of us in the car, the windsreen and windows would mist up. i noticed the 6 way heater selector switch only blew hot (or cold) air into the footwells. no other position worked. after browsing this forum, it looked like i may have had a problem with the vacuum system, possibly a pipe had come off the plenum chamber or vacuum reservoir.

so, this morning i had a look at the plenum chamber first and lo and behold i found this:

vacuum pipe off 1.jpg

a close up:

vacuum pipe off 2.jpg

i just pushed the pipe back into the elbow shaped pipe and took her for a spin. now the heater controls work perfectly in all positions.

a simple little job that just works. hope this helps anyone with a similar problem.

[lotustonybassplayer]

I just had the same problem, the elbow connector is perished, I managed to bodge it with some insulating tape does anybody know where to buy a replacement can't seem to find anything on line

[DeanG]

Good news. May all your fixes be so easy.

[Brit-Car-Nut]

The lotus part is obsolete but I believe the Triumphs use similar elbows. Look at Rimmer Brothers for vacuum line and connectors.

[Rice crispy]

I got some off ebay and drilled them out slightly to fit and it's been ok for about 5 years

[lotustonybassplayer]

just a bit of info, i got an elbow from a mini (12B2062) its used for the vacuum advance on the dizzy, perfect fit £1.60 on ebay selective mini spares shop (cant do links )

[Elanlover]

Well the timing of this post is convenient as I have now developed the same problem. Floor vent only activation of the air. I don't have a loose hose however. Now, before I start poking around (fortunately the dash is out) does anyone have any suggestions on where to start looking? Thanks!

[lotustonybassplayer]

Vacuum reservoir ? I believe left wing/fender behind wheel arch liner ?

[Elanlover]

Well I'm having a hell of a time finding this reservoir. Got the car up and liner off on the (Fed) driver's side and can't see anything. Grrr.......

Must be in the cabin?

[epipete]

Have a read of this, there are good pics and diagrams

viewtopic.php?f=37&t=21449&p=269831&hilit=vacuum#p269831

[Elanlover]

Frustration level rising.

Pretty sure the vacuum line and reservoir are ok. When I turn the dial I hear that "sucking" sound that would seem to indicate there's vacuum there. I just don't get anything but foot well breeze. No other positions engage. Any other ideas?

[Elanlover]

Here's a thought. Can anyone tell me (who's looked back there recently) exactly how the vacuum "plug" connector mates with the back of the dial control? I customized my dash several years ago and had to had extra lengths of hose to meet up to the back of the dial in its new location. So, does the end of the vacuum hosing that terminates at a large rubber plug simply plug into the back of the dial or is there something else in between? I'm now beginning to wonder if I have inadvertently crosses a few hoses.

[lotustonybassplayer]

well if the fault has only just developed, then your mods, if previously caused no problem to the distribution system then it seems that you have lost the vacuum supply. Have you checked all the hose connections under the hood and the current state of the hoses. My fault was the same stuck in the footwell area as that was the position of the dial when i lost the vacuum.

[Elanlover]

Well, as I mentioned earlier I believe that I have vacuum since when I turn the dial I do get the hissing sound. So, one would "think" that isn't the issue. And the plug does fit into the back of the dial (as I've just discovered). I'm going to pull the arch liner off again and have a good look for the vacuum reservoir and any loose hoses just the same.

[epipete]

If you have removed the 'bung' off the rear of the selector unit then you should be able to test for vacumn without any more dismantelling.

The bung is the nexus of all the hoses for the heater system only one of them draws air (ie from the Vacumn reservoire) all you do when you turn the dial is direct the vacumn through different hoses (to effect levers within the heater box). So with the bung disconnected and the engine running you should be able to feel suction via one of the holes in the bung. If you have this then vacumn is not your problem!

[Elanlover]

Had already done that and discovered that I do get "some" vacuum. I'm not sure how much I should be feeling. Its very mild to say the least. I'm going to try connecting the vacuum hose from the back of the "bung" directly to a few other hoses to see what happens.

[Brit-Car-Nut]

Blair: You should get the same vacuum as you will find at the intake manifold. Engine must be running...

Here is a diagram of the vacuum plumbing for a 6 pos LHD car:

LHD-6pos-2.jpg

Open higher resolution picture:

If you need to clarify anything, I have a spare dash control assembly and a "New, in the box" heater assembly with vacuum hoses already in place (with NUMBERS) I can take pictures of.

[epipete]

You will note that the Vacumn goes to #2 on the bung but also supplies, via a T section the hot/cold valve (which is operated by the dial on the heater control.

[Elanlover]

Well I'm definitely getting vacuum. That's for sure. I'd already reviewed the diagram you posted John to make sure I hadn't accidentally run the hoses to the wrong position on the bung and/or my extension (fortunately, my hoses still have the number tags on them). So, the vacuum and all the plumbing seem to be in order. I've directly connected the vacuum hose (#2) to all of the other hoses (one at a time of course) and still get nothing but floor air. There has to be something else preventing the other positions from activating.

I've been "trying" to figure out what hoses do what when the dial is turned. I've taken the dial apart (not advisable as it VERY easy to break - good thing I had a spare) and discovered that the dial turns a rubber "maze" (yup - a maze) inside the dial mechanism that connects the vacuum hose to another hose by establishing a channel. Since there are 6 positions and only 4 hoses to connect the vacuum to then a couple of the positions on the dial must connect more than one hose to the vacuum. So, something is just not activating the other positions.

Having a second look at the diagram you posted John I'm now wondering if I may have done something to prevent the top flap on the unit from opening thereby keeping the floor vents open. I don't know if that top vent controls all the other positions (windshield, face vents, etc.) but if it does this may be the culprit as I did move the piping a bit to try to make some room. I may have misaligned it with the top flap preventing it from opening???????????

[Brit-Car-Nut]

Can you disconnect the top flap from the vacuum motor? If the flap is jammed, you should be able to see the motor move the control knob forward for top vent and backward for bottom. You can also try to move the flap manually.

Since you said you have your dash out of the car, I thought you could see the heater assembly and thus all of the actuating vacuum motors. Any chance of some high resolution pictures?