[DML] Re: Proper operation of mode switch

["ryanpwright" <yahoo1@xxxxxxxxxxxxxx>]

Thanks Bill & Dani. Appreciate your replies. I'll go pick up a hand
vaccum pump, and checkout that section of the workshop manual to
ensure my lines are setup correctly. 

I can't help but wonder if one of my diaphragms isn't working. How can
you tell whether they're working? I know there is one of them in the
dash that moves a metal bar. I can clearly see it move, so it's OK,
but I can't see if the others have anything similar (I can see the
diaphragms themselves, but don't see any actuators coming off of them
looking from underneath the driver's side).

Also -- Is the hot/cool knob supposed to change the location of air?
For instance, I get air out the vents when it's on one setting, but
change it and the airflow from the vents stops. I've never had a car
work this way before.

-Ryan

--- In dmcnews@xxxxxxxxxxxxxxx, "content22207" <brobertson@xxxx> wrote:
> 
> 
> Pages N:01:03-09 of the Workshop Manual show graphically which
> diaphragms should be activated for each HVAC mode switch setting. Text
> at the bottom of each page also explains quite well. Page N:08:15
> documents vacuum hose routing -- if you still have factory hoses
> simply follow their colored stripes ("pipe traces").
> 
> A hand vacuum pump is invaluable for trouble shooting vacuum operated
> devices. Will verify that all HVAC plumbing is indeed vacuum tight
> from the engine compartment Tee forward (remember: my leak was under
> the console). Can also use it to manually operate each ductwork
> diaphragm individually. 
> 
> Bill Robertson
> #5939
> 
> >--- In dmcnews@xxxxxxxxxxxxxxx, "ryanpwright" <yahoo1@xxxx> wrote:
> > 
> > 
> > What is the proper operation of the mode switch? In other words, where
> > should I get air on the various settings?
> > 
> > Here's the deal: I get A/C just fine on the three A/C settings, but
> > there isn't much of a difference between them. The airflow is boosted
> > slightly when on max. Mid and low appear identical. When the
> > temperature is switched to hot, "vent" directs air at my feet,
> > "heater" doesn't seem to direct air anywhere, and "defrost" seems to
> > direct more air toward the windshield but not as much as I'd expect.
> > If I switch the temperature over to cold, all of this changes
> > completely!
> > 
> > So I dug into it tonight. The dreaded previous owner screwed up my
> > vaccumn lines. I did my best to sort them out, following the diagram
> > here (http://www.usadmc.com/dmcstore/images%5C730.gif). There was an
> > extra T where one shouldn't be, another with a missing hose, etc.
> > Anyway, I think it's all as it should be now, but the situation hasn't
> > changed any. 
> > 
> > I've:
> > 
> > 1. Rebuilt the mode switch. There are no vaccumn leaks that I know of
> > either up front or at the engine - doesn't mean they aren't there,
> > just that I don't know of them. :)
> > 
> > 2. Sealed (as best as I could) that foam behind the heater box with
> > some duct tape.
> > 
> > 3. Tried to sort out the vaccumn lines, I THINK they're correct, but
> > who knows.
> > 
> > Any thoughts?
> > 
> > -Ryan








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