My climate control system seems to have occasional senior moments. It may be necessary to press multiple buttons before it will recognize a command. After that, the entire panel seems to operate normally....and will do so for extended periods of time.

Often, I can just wait a minute and try again....to get proper response. (Sound like a bad ground?)

Originally, I’d considered the option of separating the face and cleaning the button contacts. It is 23-yrs-old. And, like the heater core, was one of the few things I didn’t touch in my “restomod” project. (Skipping the heater core didn’t prove smart since I had to do it this summer.)

Actually, I did pull apart the face-to-main-multi-pin connect, clean and replug. I also pulled the module (above accel pedal) and resoldered a joint – that repaired faulty function of the blend-door motor operation.

This problem has me a bit stumped since I’m not convinced the buttons don’t make contact and send a “command”. The “brain” just seems asleep from time-to-time. Like me! And, that main plug junction WAS one of the things I did separate/clean 2 yrs ago.

Where would you look, resolder, or clean? Thanks!

 

My guess, If it's not related to one command the long board the head unit is on warps and the contacts get intermittant. When you pulled it out to clean it did you pull up the contact fingers? It seemed to help on my 87.
I've found cracked runs in the controller (up by gas pedal) I finally striped out some 24ga CATV cable and formed it over some of the runs and soldered it down.

The parts are really starting to show their age aren't they...

JS

 

I had a similar problem with my 90 climate control, buttons would take a second or two to respond when pressed, I used electric contact cleaner in the front of the buttons (while pressing them -with ing. off) that seem to help. I now get a quicker response when pressing buttons)
** make sure when buying electric contact cleaner make sure it is safe for plastic, or it will fog or discolor buttons)
I used MAX professional contact cleaner

 

I also had simiular problem. Cleaned my button contacts with alcohol and a q-tip, works fine now.

 

you need to check the programmer circuit board. the one that is under the dash between the brake pedal and gas pedal. remove the programmer from the vehicle and disassemble to inspect the 2 resistors at the bottom left corner for solder joint failure. this will cause your hvac system to hang in heat mode. common problem on 88 and 89s.

if the solder joints have failed simply resolder or take it to a tv repair shop and let them do it. $10.00

 

Sounds like you're talking about these two resistors...


According to another post/article, resoldering those fixes the issue with the blend door MOTOR not responding. It could seem like the sytems is frozen,,,but not the same as pressing a button w/o activating the light above the button.

Since that's one of the procedure I'd already performed (as mentioned in the OP, this probably isn't my issue. It's a very good reminder for people who land on this thread though!

 

Whats a TV repair shop?

 

This is what I decided to do^^^

I pulled out the "head unit" (aka controller) and did three things: After separating the two boards, I cleaned the contacts (row of silver prongs at the top of the bottom board pictured below.) I used very fine sandpaper and metal cleaner. I used alcohol (contact cleaner) to finish.


I also cleaned all of the circuit board contacts behind the buttons. They appear to be made of copper. (I may add a pic in the near future because I thought I took a picture of this.) The contacts were fairly dark colors -- as you'd expect old copper to look. (Like an old penny). To do this, I used metal cleaner and fine sandpaper. Finished by spraying/wiping with LPS Electical Contact Cleaner. With the condition of my 23-yr-old garaged unit, I'm hesitant to say anything short of r/r and thorough cleaning -- by removing tarnish off the contacts -- would have any longevity. Hopefully, I'll have a chance to report back and say whether what I did had long-term benefit.

I also used an eye-glass screwdriver set to lift up on the prongs that press against that row of contacts I mentioned above. (This is the same suggestion mention in post #2.) IOW, I bent the pins in the largest connector -- as to increase their "spring". I got them to "sit up" higher than pre-disassembly so I'm hoping they'll press harder on the contacts now.

Not to mention the need for removal of: the speedo bezel, A/C Bezel, console bezel, and PS dash panel, one of the biggest PITA issues with this procedure is the factory didn't design the face to be separated for cleaning. There's about 30 plastic nubs that push thru the [face] electrical board. What protrudes, of the nubs, is permanently melted to seal the face module. To get it apart, simply pry it apart. (Avoid lateral movement during separation to lower the chance of damaging those nubs.) Here's a pic so you can see the nubs. This pic is after removal of the face circuit board.


Behind that face, you'll see the typical (TV) remote control button/strips that are used to make contact with AND close each circuit when pressed.


The pain was with reassembly. I used a finger-nail file to clean up the nubs. (And, reduce their mushroomed tips.) The face sortof snapped back on after this wouldn't have held. Because I broke one of the nubs, I used silicone to "glue" the button strips in place. (Really, I used a small drop on each nub before dropping the strips back on those those [nub] positioners....to hold them in place.)

The next day, I used a drop of glue on each nub before replacing the back (of the front face unit).

I plugged the boards back together, inserted them in the case, and re-installed in the car. So far so good. Everything is working great now, but enough time hasn't' passed to confirm the reliability of this procedure.

Based on the appearance of the button contacts, I think it's fair to say this was a necessary procedure. Combined with the interboard socket cleaning and soldering of the resistors (shown in the prior) thread. The steps in this thread might represent the overall overhaul needed for these late 80's Corvettes. (Probably LT's too?)




Note: FWIW, I also used a buffer to individually clean all buttons. And, I used satin urethane to provide a new, thin sealer on the A/C controller face. This helped make the outside look new (newer) again.

 

Well Greg thats just too cool. You didn't have to spend any money either!!!
Your the DIY hero now!

 

Maybe not on this project. But, it's stupid how much money I've spent on my "hot rod" since I bought it. Owning these cars -- if you attempt to keep them as new as possible -- is definitely not cheap.

If this works long-term, it'll be one of the more satisfying projects outside the motor build. And, I can finally say everything works [perfectly] on my car again. It's been several years since I could say that....try at least 6-7.