Thermostat

[STDog]

Also, I did the check recommended above -- when I crank up the temp, the air comes out the bottom vents, defrost hits the windshield, and AC comes out the dash.

The floor, vent, and dash blowers are NOT all on at the same time.  I tested all 3 and they blow only when they are supposed to. 

Guess I misunderstood.

Ok, so, high temp, you get floor vents, and low temp you get panel vents.

Lilkely a bad line or vacuum motor to the mix door then.

Maybe a bad line to the water valve too.
Did you test the water valve to see if it opens or closes when vacuum is applied?
And that it goes to the opposite state when the vacuum is removed?

I'd check the valve and vacuum motor first,
Then the lines by removing them at the control head. Apply vacuum with a hand pump there, and with a second gauge on the other end and look for leaks.

[Glen]

I’m not familiar with the ’83 system.  In the early systems the heater core was shut off only in Max A/C mode.   The heater valve came in two flavors; one was opened with vacuum the other was closed with vacuum. The shop manual should tell which one you have.  When the control (Programmer?) releases the vacuum it is vented to the atmosphere and the hose would not provide any resistance when your friend blew into the hose.

The temperature door could just be stuck.  If they stay in one position too long they stick in position and it takes more than just the vacuum motor to move them.  Once they are pulled loose they usually will work properly again.  But it could also be a bad vacuum motor or loose vacuum hose

Glen

[Guidematic]

The blend door is controlled directly by the programmer, which also directs vacuum to the correct vacuum servo that actuates where the flow id to be directed.

The programmer can be accessed by removing the glove box. You will see a rod coming from the programmer to the blend door. Change the temp on the ECC from full cold to full hot and observe the rod. Is it moving? Is it moving far enough? If the door is not fully seating in one direction or the other, the rod can be adjusted.

Overall this is a very complex system. It relies on having hot coolant as well as cold refrigerant delivered to the heater core and evaporator core respectively in order that the system can maintain the desired temperature. Plus you need reliable vacuum delivery so that the system can do its' job.

To diagnose these systems properly, you absolutely need the shop manual.

Mike

[Rick Biarritz]

Okay, I like the sound of this.  Sometime in the next few days, I will be attempting this manuever.  I have the shop manual and will consult it, but you say I can see the door in question by removing the glove box?  Also, what is your take on that vacuum tube discussed above?  If the door is "stuck" could it be because of the tube, or are the tube and the door separate issues?  How suspicious is it that when blowing into the tube there was no resistance?  Also, I could feel no vacuum pull on the tube with the AC on full blast or with the heat on full blast.  This is suspicious, right? 

Thank you all for all the help, I only wish I had a little more time so that I could have checked out these tips a bit more thoroughly.  But I am moving forward slowly.  Slow but steady. 

[Guidematic]

Sometimes the vacuum lines that are not being directly used in a particular mode are simply vented to atmosphere. That would explain the no resistance in the line, but not the absence of vacuum on full cold or full hot. Check the line under hood for cuts or splits.

Once you get the glove box out, and you may also have to remove the under dash hush panel, you will see many of the vacuum lines.

The shop manual had a vacuum schematic in it that will tell you what lines get vacuum and at what time. I would also consult the trouble shooting pages. They are listed by symptom. Be prepared to do some electrical testing, and be sure to use a digital volt meter.

Mike

[Doug Spingelt]

To answer a question a while back, the heater valve is the space-needle-looking thing in line with the coolant hose to the heater core.  It has one vaccuume hose to it that originates from the cabin.  (At least in a 75 Eldorado)  The heater core with no vaccumme applied defaults to an open position.  I know this because I cannot control it and am being baked out of the car, even with the roof off!  that is an issue for another day, but there you have it!   My car has virtualy no vaccume hoses attached to anything and I am slowly replacing them and things are beginning to work like magic. 

Good luck!

["Cadillac Kid" Greg Surfas 15364]

Rick,
Sorry to get into this so late.  I believe the band you cut off the heater water line was the restrictor (or a replacement for it) that is intended to cut down the flow of hot water to the heater core (on purpose).  Your system, as you know is a microprocessor/vacuum "hybrid" with sensors "telling" the ECC module what the conditions are and the module sending electric signals to the vacuum solenoids in the programmer causing them to open or close in response to what the module "wants" to do as far as mode door, defroster door, recirc door, and hot water valve.
I did not read all the previous responses, but the first thing I would do if I found an inoperative system of this type would be to check the sensor string for continuity, check the sensors individually for compliance with the values listed in the service manual, and then check each of the vacuum modules with a hand held vacuum pump to see if they in fact are functional.
Once I had done that I would check all the electrical and vacuum lines.  All these in order I might suspect the ECC.
Greg

[Rick Biarritz]

Okay, here is the latest.  Have not yet looked behind the glove box and/or under the dash (don't beat me up), but the part which I have called "heater valve," the part whose pivoting arm was tied up with a plastic tie is called the "heater water valve actuator."  It is clamped to one of the heater hoses and rests a mere inch from the firewall.  I did a test.  As noted earlier, I can detect no vacuum pulling on the vacuum hose that attaches to the heater water valve actuator (HWVA) at either high heat or high air conditioning -- 90 degrees down to 60 degrees.  The new data that I have is this...  The pivoting arm that had been tied down does not move either at high heat or high ac.  Is this the part that is broken?  OR...  Is the villian still likely a stuck door.  Does the stuck door cause the arm not to pivot?  I'd like to think it is the HWVA because I could replace that in 10 seconds.  However, the guy who sold it to me (a liar no doubt) but still car savvy, seemed pretty sure it was the door, and if it was the HWVA, I'm thinking he would (a) know that, and (b) replace it.  Anyway, what do you guys think?  Thanks. 

[Misfit]

I would answer the question, being as I'm here, but I'm not really familier with the newer set-ups. If I had the car in front of me to check in steps I most likely would know what to do.

Some of these vacuum operated systems will drive you to drink. I like the simple cable operated systems, like my '59 has. Slide the lever to a warmer position and the car gets warmer. Slide it to cool and the hot water control valve closes and the car cools down. Same results, just a lot more complicated on the newer cars.

I like simple. Goes with the user !!!   

MisFit

[Rick Biarritz]

I'm with you on the simple.  Look under the hood of my 69 Polara, then look under the Eldo hood!  Good God!  I don't have Ph.D. in automotive technology.

[grinch]

I'm thinking it's still in your H/C door.  Like a previous post said, the heat and a/c run at the same time.  The door is what varies the air temp.  Sorry, I don't know more about this system and I'm not right there to see the air routing.  You're going to have to locate and diagnose that temp door and vacuum diaphragm. 

[Otto Skorzeny]

Heck, your Eldo is stone age technology compared to a new car. I opened the hood on my brother's new Buick Lucerne and couldn't tell if I was looking at an engine or a backpack re-breather for deep sea diving!

The engines all covered with smooth plastic shells now so you can't even tell where the individual components are. Once you find them it's still hard to tell what they actually do.

[Rick Biarritz]

So, nobody's with me on the heater water valve actuator being the cause of the problem?  I gotta go looking for this "door"?  Oh well.

[STDog]

Rick, you can chase random ideas for weeks, replacing random parts that might be the problem, and spend lot's of cash.

or...

You can methodically troubleshoot the system, as described previously.

[Rick Biarritz]

Rick, you can chase random ideas for weeks, replacing random parts that might be the proble, and spend lot's of cash.

or...

You can methodically troubleshoot the system, as described previously.

You are correct.  Gotta go door hunting, I suppose.

[Rick Biarritz]

The blend door is controlled directly by the programmer, which also directs vacuum to the correct vacuum servo that actuates where the flow id to be directed.

The programmer can be accessed by removing the glove box. You will see a rod coming from the programmer to the blend door. Change the temp on the ECC from full cold to full hot and observe the rod. Is it moving? Is it moving far enough? If the door is not fully seating in one direction or the other, the rod can be adjusted.

Overall this is a very complex system. It relies on having hot coolant as well as cold refrigerant delivered to the heater core and evaporator core respectively in order that the system can maintain the desired temperature. Plus you need reliable vacuum delivery so that the system can do its' job.

Okay, here goes.  I removed the glove box.  I put the system through its paces (60 degrees to 90 degrees).  But I have NO idea what I'm looking for.  What does the "door" look like?  I see nothing that I would describe as a "rod".  The Haynes Manual is worthless as far as pics go for this application.   I could see NOTHING moving.  No rods pushing on any doors.  From the looks of it the programmer (dictionary sized black box) is accessed by going under the dash.  During my test, I could HEAR stuff going on, even heard what sounded like a door flopping open at one point -- the exact same sound I used to hear in my 66 Pontiac Catalina when I turned the heat on.   Am I looking in the right place?  What now?  Thanks a bunch.

[STDog]

The Haynes Manual is worthless as far as pics go for this application

That's a well know fact. The Factory Service Manual is what you need.


As for the rest, someone with more knowledge of that system needs to chime in.
I'm sure Mike will see it and offer more help. Maybe some pictures of his '85?

[Rick Biarritz]

By the way, if I verify that the blend door is stuck, or doesn't move smoothly, I've been told that the solution is to replace the programer.  Is this true?  Is that how one fixes a bad blend door or blend door rod?

[Rick Biarritz]

SCORE, SCORE, SCORE!!!!!!!!!!!!!!!!!!!!!!!!!  LET LOOSE THE PIGEONS!!!!!!  I found the arm, and diagnosed the problem!  For a novice like myself this is a big day!!!  I found a white plastic thing sitting on a small black box (forget that large "dictionary" sized thing I mentioned earlier).  This white thing appeared to be set up to pivot, and had a hose/cable on one end.  I swung it around with my hand, and suddenly I had heat for the first time ever!!!  Set on 60 degrees, I had HOT AIR.  Swung it back the way I found it, and lo, cold air.  I think it is safe to say that I found the problem, yes?  Thanks to all of you, of course.  NOW, what do I do?  Buy a new programmer?  And is that small black box on which the white arm sitting the programmer?  Thanks again, guys. 

[Guidematic]

Not to p*** on your party, but the programmer works on the command of other inputs. That's why you need the manual. You have to remember that these are very complex systems, and they even give the pros conniptions.

What you have found is that the programmer is not operating the blend door. It could  be a programmer problem, but it may also be something that is influencing it like a vaccum or electrical connection, or a command from the ECC head in the dash.

Mike