Author Topic: 1984 DeVille AC Problem - Bizarre!  (Read 583 times)

Offline P. Manoogian

  • CLC #29766
  • Posts: 336
  • Name: P.Manoogian
1984 DeVille AC Problem - Bizarre!
« on: April 10, 2019, 04:16:42 PM »
Car came in with bad compressor that had been previously changed. (reman)


It did NOT have the button switch on back. (Clutch wire is grounded to intake manifold) I've seen originals with button switch acting as the ground.


Purchased a rebuilt w.o. a button switch.


Installed with new accumulator, orifice, oil,, vacumed out, recharged with 134 which was there.


Started car - ice cold A/C BUT....BUT...compressor would not shut off.


Followed All Data schematic which indicated that power module was bad.


Have since tried 5...yes 5 used power modules AND NOT ONE allows compressor to engage!


I know these modules are problematic, but can 5 all be bad (and one came from a car that has sat but the owner said it worked) The other 4 were in a local scrap yard removed before the Klunker Law...


Any thoughts?


Thanks
1961 Eldorado - Shell Pearl/Mauve
1959 Coupe DeVille - Vegas Turquoise
2012 CTS Coupe- Crystal Red
1970 AMX

Offline chrisntam

  • Posts: 3472
  • Dallas, Texas
  • CLC Number: 29206
  • Name: Chris Jessen
Re: 1984 DeVille AC Problem - Bizarre!
« Reply #1 on: April 10, 2019, 08:59:02 PM »
Really can't help but I'll give the post a bump.

To clarify, you said a/c blows cold but the compressor wouldn't shut off (disengage), but then you say it won't engage.

When the a/c worked on the car previously, did it engage / disengage properly?

Is the purpose of the switch to protect the compressor when the charge gets low and keep it from engaging?

Not helping much but it sounds like the system is not cycling like it should.
1970 Deville Convertible 
Dallas, Texas

Offline P. Manoogian

  • CLC #29766
  • Posts: 336
  • Name: P.Manoogian
Re: 1984 DeVille AC Problem - Bizarre!
« Reply #2 on: April 10, 2019, 09:23:56 PM »
Yes, that switch is to provide protection in the event of a low charge. The Roman compressor was toast. The replacement compressor works fine, it just wont shut off with the blower module the car came with. 5 used modules wont turn the compressor on






1961 Eldorado - Shell Pearl/Mauve
1959 Coupe DeVille - Vegas Turquoise
2012 CTS Coupe- Crystal Red
1970 AMX

Offline TJ Hopland

  • Posts: 10193
Re: 1984 DeVille AC Problem - Bizarre!
« Reply #3 on: April 11, 2019, 09:02:01 AM »
The aftermarket compressors seem to be like the aftermarket blower motors which require more power to operate than the originals do.  This extra power seems to be very hard on the electronic modules.  I don't remember the exact numbers but what looked to be an OE compressor that had sized and tore up the clutch and bearings had something like a 4 amp draw.   The vintage aftermarket one was drawing like 6 amps.   I think it ran for about a week before the module popped.

I'm not sure how much change there was between 80 (first year for the digital system) and 84.   On the 80 there was a signal line from the 'brain' inside the car that went to an electronic relay that happened to be located in the blower module.  I don't remember if its a positive or negative signal.  It didn't have anything to do with the blower or blower operation they just decided it would be a good place to put it.   My fix was to wire in a standard automotive relay.  Worked fine.

How I diagnosed it was found the diagram and was able to verify that when it was set to AC that signal line was doing what it was supposed to do and I had the power available at the module.   That told be it was that part of the module that was bad. 
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

Offline P. Manoogian

  • CLC #29766
  • Posts: 336
  • Name: P.Manoogian
Re: 1984 DeVille AC Problem - Bizarre!
« Reply #4 on: April 12, 2019, 08:52:36 AM »
Indeed there is a guy in California who rebuilds the modules. He is on e bay but his number is listed. We spoke and Ibwill send him two modules that wont engage the compressor and the one that wont allow it to shut.


Thanks
1961 Eldorado - Shell Pearl/Mauve
1959 Coupe DeVille - Vegas Turquoise
2012 CTS Coupe- Crystal Red
1970 AMX

Offline TJ Hopland

  • Posts: 10193
Re: 1984 DeVille AC Problem - Bizarre!
« Reply #5 on: April 12, 2019, 10:17:28 AM »
Its good to hear there is someone out there that is able to fix these.  I would imagine its like the ECU's that Bruce fixes or climate control that Tim does.   Once you have more or less reverse engineered it and built some test rigs they are not that difficult to repair.   They most likely tend to fail in the same ways so once you have that figured out the common failures its just finding the parts or coming up with a substitute.   

On the ones I looked at that have failed both blower and compressor I have been able to see what looked like bubbles in the potting material around what look to be transistors.  Potting is where they pour an epoxy material over the circuit board to protect it from physical damage.   The potting presents an additional challenge for the repair because first step is removing the potting material to access or even troubleshoot the board.   I have tried to remove the potting on a couple of blower modules and level ride modules and both times did further damage so just figuring out that step can be quite the process. 
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

Offline spolij

  • Posts: 826
  • CLC Number: 31408
  • Name: John Spolidora
Re: 1984 DeVille AC Problem - Bizarre!
« Reply #6 on: April 13, 2019, 09:22:18 AM »
sounds like the compressor is not the problem.

Want to hear weired yesterday my climate control was running and the dash module wasen't even hooked up.

Offline P. Manoogian

  • CLC #29766
  • Posts: 336
  • Name: P.Manoogian
Re: 1984 DeVille AC Problem - Bizarre!
« Reply #7 on: April 13, 2019, 10:13:04 AM »
The attached wiring diagram is from all data. The colors do not match the module plug. Service manual on order

1961 Eldorado - Shell Pearl/Mauve
1959 Coupe DeVille - Vegas Turquoise
2012 CTS Coupe- Crystal Red
1970 AMX

 

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