87, electronic climate control. No matter what I set it to, it was blowing air everyplace at once. Took off the passenger side hush panel and operated the control while watching the vacuum motor. No action. I reached up and pulled the lever and YEEHAH, it starts working. I tried it about 100 times and all is good. Now whats up? Do I need to lube something, or replace a part ? Any input is appreciated as I'm climate control spoiled (never take the top off) and want to keep it maintained. 116 K on the car and not many typical C4 problems, just mods and tires so I cant complain.

 

Assuming it's electronic air, the temp door isn't controlled by vacuum - it's an electric motor. Motor is controlled by the Programmer (above and to the right of the accelerator) and it moves the door to provide nothing but cold air, nothing but heat, or a combo of the two. Input signals to the Programmer are what you select at the Controls and the inside and outside temp sensors. At Auto 60 or 90 the inside and outside temp sensors are ignored and you either have full cold or full hot. Dash Controls - with the assistance of the Programmer - determines how long it takes to move the door in either direction by applying voltage on one side until it stops moving. That voltage then switches wires and moves it in the other direction. (The voltage signals are the Tan/Black and Yellow wires - when one is hot, the other is ground). Position is kept in memory until you remove power (pull the courtesy clock fuse or disconnect the battery) at which point, when it's powered back up, nothing works for a couple of minutes while the door is cycled. If the door isn't moving it's either jammed (as you found out), the linkage is broken (it's held together with a plastic clip), the motor has died (don't know of anyway to service it) or the Programmer or any of it's inputs are broken. A short in the feedback circuit will generate a trouble code and cause the LED below the outside temp readout to blink. Access codes by holding the Ext Temp and Auto Button. A mode number will display. Press the Warm button until it shows an "8". Press the Cool Button for the Codes. 00 means there's nothing. 01 is the Temp Door motor - feedback circuit is open which is the Dark/Green Wire from the Programmer to the Dash Controls (and the wire that's telling the Assembly how long it's taking to move the door).

 

Thanks for a good description of the system. I do have electronic control, but there is a vacuum diaphram operated trap door at the passenger kick panel. Thats what I moved by hand.

 

It could have just been a little sticky. Spray a dab of white lube on the lever hinge and it might just continue to be fine.

 

[IMG][/IMG]

CK/NC I think I will make a run for some lubriplate when they have a caution during the cup race.

 

That didn't take long, they already had one! Actually I was thinking of white lithium spray lube like we use on hinges, latches, etc. but Lubriplate #105 will work too. I've got a zillion tubes of it, if you were here I'd just give you one. Work perk.... I get one with every overhaul I do but it never takes a whole one so I just bring the excess home.

 

That solenoid controls air flow from the windshield or fresh air inlet - normally open, vacuum is applied at Auto 65 to 60. That shuts the door so that the majority of air flowing across the Evaporator Core is at the lowest possible temperature giving it the best possible vent temp (just like a central a/c unit). There is a bleed in the line that keeps it from flopping around during borderline conditions. Test the solenoid by applying 10 in of vacuum. If the linkage moves, put the controls at anything other than 65 or 60 and make sure that it doesn't move. Then, at 65 or 60, you should be able to see it shut. If not, the line is broken or the Programmer is shot (assuming all the other doors are moving; ie, you've got vents, heat, defrost, etc). However, re-reading your post, sounds like you've got air out of the defroster, vents and heater??? Default a/c is through the vents with a tad through the defroster and heater ducts. Full flow through everything would be unusal. System also sucks the defroster door shut except with defrost (at which time it sucks it open). If all it has is defrost, then the vacuum source would be suspect. It's from the Plenum, next to the fuel regulator, pass the left side of the Distributor where it tees off through a check valve - one side goes through the Firewall with the ECM harness (right side) - other side to Cruise and the Vacuum Tank. Verify the check valve isn't broken. Otherwise, you'll need to see if vacuum is making it to the Programmer - it's the black line. If it is, you'll need to see if vacuum is being applied to all of the solenoids when commanded. Red and Tan lines go to the Defrost door - one or the other should always have vacuum applied. Blue is vents - vacuum with Auto or Econ at 60 or Bi-level at 60 to 90. Pink is heat - vacuum with Auto 90 or Bi-level 60 to 90. All of the solenoids - with the exception of the one you've found are on the left side of the Heater Box, to the right of the Programmer. Access by removing the driver's side hush panel. Most flow problems are either at the source or check valve or the Programmer is shot.

 

Sun, thanks again. I have the Helms, but sometimes it not as clear as it could be. Your description is very clear. Back when I had my 86, the controller was being a problem. It was not responing to input. I met Gordon Killibrew at BowlingGreen and he told me how to disassemble it and clean the contacts. Did it and it worked great. That will be my next step. Probably be 2 weeks before I get a chance and that will give me more time to see how its behaving.
Vacuum lines under the hood look good going into the firewall. And yes I did have air blowing everywhere. This sound like default mode. I posted this because I was not sure of what was going on. Still not sure, but it was working good after I got that lever moving. I drive it every day and its hot here, so I will find out soon if its going to act up.
THANKS again.