Question No. 1: Does anyone know if controllers vary between model years? I have a controller that came out of an unknown model year and it had already had a 2 amp relay "fix", but the circuitry of the fix doesn't correspond to Dr. Bob's fix circuitry and the relay is not the same configuration, so the points on the board that need to be de-soldered are not the same.

"So what?" say I. Just find the analogous points on the new 5 amp relay and solder them per Dr. Bob's fix. Doesn't seem to be that easy because the board is butchered and some of the circuits appear to be very adulterated. And no one so far seems to know how this configuration came to be; all boards are the same for all model years they say. Perhaps this controller came out of an earlier car than mine ('86.5), or it has been modified.
In a fit of irrationality, and an hour prior to leaving on a long trip, I swapped my '86.5 controller for another one at a reputable shop. Mine had quit the day prior to my trip, after performing flawlessly for 1 1/2 yrs. The swapped controller worked for 2 days, and then it quit in the middle of Nevada

Question No. 2: Does anyone have a spare controller that I can buy to serve as a parts donor to my controller? In particular, the board in the controller must be good, but the relay can be toast. I will implement another relay fix. Otherwise, I must repair the circuitry on the board which has come literally unglued. It has been overworked.


Thanks for anything that comes to mind.

 

When you get the next life wrestled out of whatever controller, consider installing a standard garden variety 20-40 amp relay underhood patched into the AC clutch power lead. The input side becomes 85 to 86 to ground: fused 12v to 30 to 87 to the clutch becomes the switched leg - placing the wear and tear at that relay and avoiding the controller.
Some other wiser person suggested installing a large diode on the controller output lead to minimize the inductive feedback from the AC clutch - that eats the puny little relays contacts, if that is what this issue happens to be.

 

As I understand it, that is precisely the subject of this issue. I spent last night patching my weirdly modified controller board to accept a 10 amp relay, but am not sure I got the circuitry correct. And the board is a mess. Too many patch jobs and holes where someone has soldered in another attempted relay fix. Probably best to trash the board in it, but the day will come when someone will need it in absence of anything better.

 

Ron, it's possible that board could be repaired or otherwise turned into a reliable unit by perhaps soldering certain connections at the other end of the trace. Is the unit out of your car where I can look at it?

 

Ya know, there's not a whole lot to the part that tells the compressor to run. That takes up one of the contacts in th controller. The other contact tells the HVAC brain that you pushed the button, so it can do a better job of manipiulating flaps and the heater valve.

The schematic for the dash controller looks the same between the '86 and the one for my '89.

As Dave points out, you can do an awful lot of repairing on these boards by jumpering bad traces with some bus car or insulated connections where needed.

I have a 'spare'/donor controller around here someplace, unknown origin, but with the same problem you have: a butcher been at it already. I know it can eb fixed, I just need some time and a reason... I guess I need to stroll by the local Radio Shack and grab one of their relays, adapt it into the board so it works, then publish the puctures with a new how-to-do-it guide.

Ron, send me a pitture of the damaged board for an assessment of repairability. Dave has some experience with industrial controls and may be able to give you some help/guidance on getting yours back in service.

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Good thing it was only in the high 90's yesterday when we left San Jose. On the way up, we saw temps in the 105+ range while cruising through the King City to Salinas area. Yesterday, that same stretch was in the mid-70's to mid 80's, then hotter for a bit as we continued south on 101. We used the AC until the sun went down on us around Santa Barbara and we were cooled some by the ocean breezes. Nice drive except for traffic slow/stop through Santa Barbara.. at 9PM! Go home, people, and get out of the way! Oooops, sorry!

 

If my single brain cell remembers it right from last year,
the model change to the HVAC control head was around '83.5.
So any late S/S4 plus unit will work.
If unmolested that is. Just checked 928Intl's great site.
They list 83.5 - 90. And then 90 Plus control heads.

Ernest(NYC)

 

Here are some shots of the mess. The green wire bridge was an attempt to remedy the strip that fell off of the board. Obviously someone had been to work on this board in the past...several times. If you can see them you will spot a couple of vacant holes where the other relay had been attached and notice that the #7 and # 8 leads from the relay are attached up at the edge of the board which is not consistent with the points on the 2 amp relay which is much smaller than the 2 amp relay that was installed on the board originally.
Pardon the focus quality please.

 

Looks very fixable to me, near as I can tell from the pix. Bring it on by and we'll fix it up.

 

Damn ! I was looking in Veggie Love for some nearby hotties and your post triggered a notice and now I lost my place.

OK, when are you inclined to interupt your frenzied search for the noble pursuit of employment to gaze a little more closely at this cluster XXXX of a controller?

 

Maybe tomorrow around 11:30am?

 

Well, this story may have a happy ending after all thanks to Dave (Sharkskin).
The stop at his house was fruitful and he found a poorly soldered joint and we checked the system and found it should work once it is recharged and I change the mangled compressor pulley. Thanks Dave.

I will need to use Dave as a structural consultant. He tends to take no chances when it comes to installing lighting and storage systems in his garage. Ask him to post photos of his unique lighting support device.

Now its off to San Carlos Radiator for a recharge and then its "cool city" for me.

 

So you're getting it recharged today? Wow, I guess you really ARE desperate to have the AC working again.