Chevy truck heater

"Whitelightning" <white.lightning2.DeleteThis@verizon.net> wrote in message
news:IE0Dd.13024$1U6.12444@trnddc09...
 >
 > "AndrewS" <UseLinkToEmail.DeleteThis@AutoForumz.com> wrote in message
 > news:41dc748f$1_2@alt.athenanews.com...
  >> I have a '91 Scottsdale, 4.3L, and the heat is always on. I can move
  >> the controls from cold to hot, a/c to vent, or whatever and all I get
  >> is heat. Even with the controls in the off position, hot air comes
  >> through to my feet. Any ideas? Thanks.
  >>
  >>
 > As you move the control between normal ac, bi-level, vent, defrost does
 > the
 > air flow move?
 > If not check the vacuum lines and the vacuum selector switch. If the air
 > flow does move, then there could still be a problem with the vacuum
 > switch,
 > or the blend door is stuck, or the dash pot that moves it is shot.
 > Whitelightning

No vacuum on this year and model; all electronic. Sounds like either the
blend door actuator motor is shot, or the linkage between the motor and door
is shot. The doors do tend to get "sticky" over time but if it was stuck
and the motor fried I'm sure he would have smelled it!

Doc


 >
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""Doc"" <noway.DeleteThis@nope.com> wrote in message
news:2o-dndUGZsTNPEHcRVn-3g@adelphia.com...
 >
 >
 > No vacuum on this year and model; all electronic. Sounds like either the
 > blend door actuator motor is shot, or the linkage between the motor and
door
 > is shot. The doors do tend to get "sticky" over time but if it was stuck
 > and the motor fried I'm sure he would have smelled it!
 >
 > Doc

Gesh that's what I get for making an assumption that a 91 full size would
be the same as my 91 S-10 Blazer.
Whitelightning<!-- ~MESSAGE_AFTER~ -->
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"Whitelightning" <white.lightning2 RemoveThis @verizon.net> wrote in message
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 > Gesh that's what I get for making an assumption that a 91 full size would
 > be the same as my 91 S-10 Blazer.
 > Whitelightning

I wish it was a vacuum actuated system. Just more shit to go wrong with an
electrical system, and it's harder to service than the vacuum-based systems.
Vac lines and pots are usually pretty easy to get at and service, the
electric motors are a real bitch and a half to get at..........kinda noisy
too.............ol' Blue sounds like a dairy cow mooing when she opens and
closes the recirc door, he he he.

Doc<!-- ~MESSAGE_AFTER~ -->
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The air flow does move between vent, bi-level, heat, etc. I removed the cover that directs air on the blend door and it does move from open to closed between heat/off and ac/vent so the actuator motor and linkage is working.
A friend suggested the heater shutoff valve (?) might be stuck open.
Thanks,
AndrewS
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"AndrewS" <UseLinkToEmail.TakeThisOut@AutoForumz.com> wrote in message
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 > The air flow does move between vent, bi-level, heat, etc. I removed
 > the cover that directs air on the blend door and it does move from
 > open to closed between heat/off and ac/vent so the actuator motor and
 > linkage is working.
 > A friend suggested the heater shutoff valve (?) might be stuck open.
 > Thanks,
 > AndrewS

Too bad yer' truck don't HAVE a heater shutoff valve!

Doc<!-- ~MESSAGE_AFTER~ -->
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"AndrewS" <UseLinkToEmail RemoveThis @AutoForumz.com> wrote in message
news:41dc748f$1_2@alt.athenanews.com...
 > I have a '91 Scottsdale, 4.3L, and the heat is always on. I can move
 > the controls from cold to hot, a/c to vent, or whatever and all I get
 > is heat. Even with the controls in the off position, hot air comes
 > through to my feet. Any ideas? Thanks.


I had a similar problem with the AC head unit in my 1990 Scottsdale.
I believe that the same system was used in the 1991 model with a
re-circulating mode button added perhaps in 1992. If your unit has the
re-circulating mode, you are probably using it as a temporary
workaround.

Do all of the features of the AC climate control selector seem to work?
In other words, does the screen show some movement of the indicator
between the icons? If this is the case, the control unit may be working
properly, but there may be trouble with the electrical connection.

To access the AC control on my truck, I needed to take out four screws
to remove the plastic surround covering the edges of the dashboard.
After this, there were a couple of screws holding the AC head unit into
the dash. After removing these screws, the AC control could be pulled
out of the dash and I could access the clip which connected it to the
wiring harness. Go gently when working with these plastic parts because
after 14 years of residing under the dashboard, they have probably
become brittle. And don't over-tighten the screws when putting the
dashboard back together.

It was corrosion in this connection which caused a number of problems
(no hot/cold temperature control, no control of air flow, inability to
select the AC mode, etc.) with the AC control on my truck. Unplugging
and re-plugging the electrical connection solved my problem and it might
solve yours. Using a no-residue contact spray is also beneficial. At
this point, you can test out the system before re-installing the AC
control.

Hope this helps.

PS: I also traced some mysterious problems with the stereo to its
connections to the wiring harness. The stereo on the 1990 truck
contained three components: The tuner, the equalizer/cassette and the
under dash amplifier which was behind the ash tray. Unplug, clean and
re-plug all of the stereo connections and this should fix things.<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: Chevy truck heater 

It sounds like the same truck! I can move the display between cold and hot and all the icons work. I've also got the mysterious radio problems, so the connections may be the problem. I'll check and let you know.
Thanks!
AndrewS
 >> Stay informed about: Chevy truck heater 

Well, I've taken the dash apart, unplugged and cleaned the contacts on the connectors for the heat-a/c controls and I still get heat all the time.
I'm stuck.
 >> Stay informed about: Chevy truck heater 

sounds like your temp door in your AC/heat system is stuck or not
working properly. THe A/C head unit could be screwed up too.

you'll need to locate in the Heat / AC duct work where a door controls
the input of heat from the heater and have someone move the controls
on the A/C control head to see if this door is moving.

Many of the temp doors are controlled by vaccum (not sure on yours)
and the old manual style A/C head unit had a cable that controlled the
temp door.

do you get cold air out the A/C vents if you turn on the A/C and
select the A/C vents? Does the defrost blow out on the windshield
when you select that?

On 6 Jan 2005 23:32:05 -0500, AndrewS <UseLinkToEmail DeleteThis @AutoForumz.com>
wrote:

 >"AndrewS" wrote:
  > > It sounds like the same truck! I can move the display between
  > > cold and hot and all the icons work. I've also got the
  > > mysterious radio problems, so the connections may be the
  > > problem. I'll check and let you know.
  > > Thanks!
  > > AndrewS
 >
 >Well, I’ve taken the dash apart, unplugged and cleaned the contacts on
 >the connectors for the heat-a/c controls and I still get heat all the
 >time.
 >I’m stuck.

---
Elbert Clarke
elbert.clarke@**adelphia.net
remove ** to email<!-- ~MESSAGE_AFTER~ -->
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"AndrewS" <UseLinkToEmail.TakeThisOut@AutoForumz.com> wrote in message
news:41de10c5$1_4@alt.athenanews.com...

<<Well, I've taken the dash apart, unplugged and cleaned the contacts on
the connectors for the heat-a/c controls and I still get heat all the
time. I'm stuck.>>


I don't want to put you to any more trouble. The cause is probably
either the control or the motor which operates the vent door. I had my
original control replaced under warranty and then when the second one
started acting up, I was able to fix it for 6 months at a time by
fiddling with the connection.

I do know that GM had so much trouble with that control box that your
dealer will probably have it in stock. Last year when I checked
availability and price, the unit was in stock at $129.

Whenever the temperature selector was moving in my truck, there was
always a little whirring noise which I assumed was a motor moving the
heater vent. I doubt that you are hearing any such noise if the
temperature is not changing.
 >> Stay informed about: Chevy truck heater 

No cold air at all. I can move the flow between vent, floor and windshield, but I never get cold air.
 >> Stay informed about: Chevy truck heater 

One thing I always wondered is this.
Vacuum leaks can cause a poor running engine, because air is introduced
after the air/fuel mixture.
Are say the vac controls, or wiper on an older car, "pre-carb"??
Or, can a rough running condition be caused by the failure of one of these
puppies? Cuz then that's a dumb ass design....

GMC Gremlin

""Doc"" <noway RemoveThis @nope.com> wrote in message
news:K9udnSbHTuLGOEHcRVn-hg@adelphia.com...
 >
 > "Whitelightning" <white.lightning2 RemoveThis @verizon.net> wrote in message
 > news:rp1Dd.16798$Y57.15888@trnddc08...
 >
  > > Gesh that's what I get for making an assumption that a 91 full size
would
  > > be the same as my 91 S-10 Blazer.
  > > Whitelightning
 >
 > I wish it was a vacuum actuated system. Just more shit to go wrong with
an
 > electrical system, and it's harder to service than the vacuum-based
systems.
 > Vac lines and pots are usually pretty easy to get at and service, the
 > electric motors are a real bitch and a half to get at..........kinda noisy
 > too.............ol' Blue sounds like a dairy cow mooing when she opens and
 > closes the recirc door, he he he.
 >
 > Doc
 >
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"GMC Gremlin" <phake.TakeThisOut@psudo.com> wrote in message
news:rHGDd.79263$uM5.49818@bgtnsc05-news.ops.worldnet.att.net...
 > One thing I always wondered is this.
 > Vacuum leaks can cause a poor running engine, because air is introduced
 > after the air/fuel mixture.
 > Are say the vac controls, or wiper on an older car, "pre-carb"??
 > Or, can a rough running condition be caused by the failure of one of these
 > puppies? Cuz then that's a dumb ass design....
 >
 > GMC Gremlin

No vacuum is exempt from causing driveability issues as the air ends up in
the intake stream one way or another, beit via a vacuum port on the carb or
intake manifild iself.

To answer your question, if you get a vac leak in one of these lines it will
cause the same problems as a vacuum leak elsewhere. Typically the vacuum
feed to these accessories is pretty small, so even a wide open line ain't
gunna fubar things too badly.

Very easy to troubleshoot though. Find the line that won't hold vacuum and
replace it or the pot it's connected to!

Doc


 >
 > ""Doc"" <noway.TakeThisOut@nope.com> wrote in message
 > news:K9udnSbHTuLGOEHcRVn-hg@adelphia.com...
  >>
  >> "Whitelightning" <white.lightning2.TakeThisOut@verizon.net> wrote in message
  >> news:rp1Dd.16798$Y57.15888@trnddc08...
  >>
   >> > Gesh that's what I get for making an assumption that a 91 full size
 > would
   >> > be the same as my 91 S-10 Blazer.
   >> > Whitelightning
  >>
  >> I wish it was a vacuum actuated system. Just more shit to go wrong with
 > an
  >> electrical system, and it's harder to service than the vacuum-based
 > systems.
  >> Vac lines and pots are usually pretty easy to get at and service, the
  >> electric motors are a real bitch and a half to get at..........kinda
  >> noisy
  >> too.............ol' Blue sounds like a dairy cow mooing when she opens
  >> and
  >> closes the recirc door, he he he.
  >>
  >> Doc
  >>
  >>
 >
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