1975 Eldorado Wiring diagram

Obie Technician Washington Posted   Latest  
Resolved
Electrical
1975 Cadillac Eldorado 8.2L (S) 3-spd (THM425)
No A/C

My neighbor found his bucket list car. This Eldo was stored for 37 years and has 40 k original miles. It cleaned up to an amazing standard, like new!

The auto climate control is inop. There are multiple problems but I have started with the basics. The fan goes to full in defrost but is stuck on low key off or on. He purchased a book on the internet to trouble shoot the climate control. The wiring diagram seems to be correct, but only includes the climate system.

The first test I did was to check the heater enable switch on the left head. When the wire is grounded the door buzzer sounds! Key on or off. In addition the wire is the wrong color according to the diagram in the trouble shooting book.

My question is where can I find the correct diagram for the whole car? There doesn’t seem to be these diagrams available at the sites I have found.

Thoughts? Thank you.

0
Stephen Technician
Tennessee
Stephen
 

Alldata, library section, will send them by email. I thought Mitchell also had old car manuals available.

+1
Ð Awarded
Agree
James Owner/Technician
Massachusetts
James
 

Those auto climate controls are notorious for going bad.

+1
Ð Awarded
Agree
Matthew Owner/Technician
Oregon
Matthew
 

I have more and probably the climate stuff too. Let me know if this matches up.

+1
Ð Awarded
Thanks
Glenn Owner/Technician
Texas
Glenn
 

Back in the day HVAC Climate control had there own manual for these vehicles. I recently finished up a 65' Pontiac Bonneville and it was an interesting chase trying to track down repair information. Look specifically for Climate control system manuals is my advice.

0
Ð Awarded
Matthew Owner/Technician
Oregon
Matthew
 

I too seem to recall the climate stuff being separate, These were the quick and dirty ones I had access to right now. I'm pretty sure I have manuals for the old stuff in the shop. I did a 63/64 Cadillac A/C swap that had me ending up with a lot of the old stuff. Finding the Vacuum diagrams on those was the hardest

0
Ð Awarded
Glenn Owner/Technician
Texas
Glenn
 

As I recall. many of these had a module mounted to the HVAC case under the hood and they were a common failure issue.

0
Ð Awarded
Raymond Mobile Technician
Michigan
Raymond
 

if u have a direct hit account or know a shop that has a subscription they will e-mail a diagram for the complete system for you , I know that's what I had to do for my 1960 impala HTH

0
Ð Awarded
Paul Mobile Technician
Massachusetts
Paul
 

I have an extensive automotive library that I've accumulated over my 40 plus years in the business. I'll look into my archives and let you know what I find. I'm more than happy to help you or any other member with information. That is the main reason I started accumulating all these manuals from shops that were closing up.

+1
Ð Awarded
Thanks
James Owner/Technician
Saskatchewan
James
 

Don't have any decent diagrams, but the fan will not pick up speed, except in defrost, if the engine temp switch is broken or disconnected. There should be a temp switch somewhere in the intake manifold, but I'm basing this thought off the accursed Volvo 760 that used the GM automatic climate control in the 80's.

0
Ð Awarded
Angelo Instructor
Missouri
Angelo
 

I have the '75 big sideways Motor Manual for that application. Let me know and I will take them over to the college and scan the images.

0
Ð Awarded
Mark Owner/Technician
Maine
Mark
 

Have you tried ClassicCarwiring​.​com …?

0
Ð Awarded
Al Technician
Ontario
Al
 

If I remeber correctly those systems had a blower lock out circut to prevent the blower motor for blowing cold air until the engine warmed up. It was a single wire on a temprature sensor mounted on the back of the cylinder head (I think it was the passenger side head). Unplug that wire and see if the blower functions normally if not ground it and see if it works. I can not remeber if it was…

0
Ð Awarded
Dennis Owner/Technician
Utah
Dennis
 

CLASSICCARWIRING​.​COM These come in a small and large size and are color and laminated , I order one for every classic car we repair

0
Ð Awarded
Mark Owner/Technician
Maine
Mark
 

Myself as well. Make fantastic wallpaper.

0
Ð Awarded
Obie Technician
Washington
Obie Resolution
 

Wow! All of the replies are great. As a retiree I do not have access to the normal SI. When you leave the trade it is a shock to scramble for info. Today I will use these suggestions and obtain what I need. Thanks to all that replied. I have a book on the climate control. The first test I tried was the cylinder head temp switch. The wire color does not match the diagram in the book, and when it…

0
Resolution Ð Awarded
Dennis Owner/Technician
Utah
Dennis
 

Let me know what parts you need for the climate control I have some in stock still - I also have a great dash pad and panels and other items if you need them

0
Ð Awarded
Obie Technician
Washington
Obie
 

Will do! Those parts must be rare! The interior of this car is pristine. Soft leather, perfect door panels etc. Too bad it is pumpkin colored. I will look it over carefully in case there is anything damaged.

0
Ð Awarded
Glenn Owner/Technician
Texas
Glenn
 

Hi Obie, I remember that being a popular color along with lemon yellow and mint green.

0
Ð Awarded
Obie Technician
Washington
Obie
 

Dennis, I found the vacuum unit on the programmer is bad. That is my current endpoint. If that is something you have contact me at … Thanks

0
Ð Awarded
Adam Owner
Arizona
Adam
 

Since the programmer is responsible for blower control, I'd check the connector and ground there first. It is in passenger footwell. It is pneumatic as well as electric, so there could be a vacuum hose leaking as well as corrosion on the ground

+1
Ð Awarded
Agree
Obie Technician
Washington
Obie
 

Thanks. I will check that out. There is a mystery hose loose in the engine compartment.

0
Ð Awarded