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Who has the 70's climate control trouble shooting guide?

Started by TJ Hopland, June 09, 2014, 10:28:28 AM

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TJ Hopland

Who has the 70's climate control troubleshooting guide?   And was 73 a year that was covered?

For those that have used it was it much more helpful than what is in the factory service manual?    I assume the factory manual was written for use with the factory tools so that is one reason this other guide was needed?

The system in my 73 had gone from kinda workable last fall to totally wacky and unpredictable this season.

Last night was driving the car home from storage and tried the heat.   Cranked it to HI and 85 and as expected it started blowing heat as it should.   Pulled up to a stop light and thought I was going to have to just give up and put the top up because I was still cold and noticed that it and switched itself to full AC.   In the past it would sometimes go wacky if I had it say set at 70 auto but it always heated if I went to 85 or cooled if I went to 65 so I was getting by for how often I needed climate control but now it seems like I can't even force it to do what I want so I will have to fix it.
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

Jeff Moffo

Have you checked with Cadillac Tim?
www.cadillactim.com

He is great and REALLY knows his stuff.  He has also written manuals on troubleshooting!

Good Luck,
Jeff
Jeff M
North Jersey
Best of all, it's a Cadillac....
'76 Coupe DeVille - Claret (Sold)
'73 Series 60 Fleetwood (Sold)
'76 Coupe DeVille-Dunbarton Green

TJ Hopland

I knew there was someone, just never paid that close attention before because mine kinda worked enough to get me by. 

Sent Tim an email. 
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

Scot Minesinger

Yes Cadillac Tim's book is really great.  It is the shop manual condensed plus many helpful techniques not in the shop manual.  I like the parts where he would write for example "fan does not operate" and he goes thru every step to check it.

Almost every year is different (except for sure the 69 and 70 are one book).  You need to order one for the 73.  The 65 - 68 seem to be the easiest to work on in consideration of everything.  The 71 - 76 are easy unless you have to replace a heater core or evap.  The 64, 69, & 70 are real hard to get the dash control unit removed and reinstalled, plus the 69 & 70 it is real difficult to get the interior part with dampers and actuators that connects to heater removed.

The wiring harnesses in the mid 70's are real bad and sometimes you think you made the connection, but the spade and wire backed out of the plastic connector - visually check this after finished - this bit me bad once the first time.  Every 75 and 76 I have worked on suffered this problem and repairs to CC include fixing wiring harnesses.  GM made replacement wiring harnesses because of this and they are real high quality - there may be some NOS ones out there.
Fairfax Station, VA  22039 (Washington DC Sub)
1970 Cadillac DeVille Convertible
1970 Cadillac Sedan DeVille
1970 four door Convertible w/Cadillac Warranty

"Cadillac Kid" Greg Surfas 15364

TJ,
Just a suggestion.  If the Automatic Temperature Control (ATC) was working correctly when you put the car in storage it might still be in a state of "hibernation". Cycle the temperature control a few times while driving slowly and see if things don't wake up. If the fan cycles from full speed through low back to full speed while "
cycling" the ATC via the temperature control dial, and if the air (on heating) starts out at the floor and ends up (on full cooling) through the dash, you just might have a sticking tmeperature control door or its linkage.  Give it a chance to wake up before you tear into the system.
Greg Surfas
Cadillac Kid-Greg Surfas
Director Modified Chapter CLC
CLC #15364
66 Coupe deVille (now gone to the UK)
72 Eldo Cpe  (now cruising the sands in Quatar)
73 Coupe deVille
75 Coupe deElegance
76 Coupe deVille
79 Coupe de ville with "Paris" (pick up) option and 472 motor
514 inch motor now in '73-

TJ Hopland

I would not say it was working correctly before storage but it worked a lot better than it does now.   Thanks for the tips though.  I think I am going to order one of Tim's books.   I have the shop manuals and lots of tools and skills fixing similar stuff so I'm sure I could figure it out but it sounds like Tim's book may save some time which I have been a little short on recently.   
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

Scot Minesinger

Tim's book saves time.  You can get much of the info thru the shop manual and experience, but it costs time to do it.  I have fixed more than a dozen CC in the last two years, but I still use Tim's books.  Plus you can call and gives tips that saves even more time, like on a 76 the fan would not come and he said relay and that was it-saved me time.
Fairfax Station, VA  22039 (Washington DC Sub)
1970 Cadillac DeVille Convertible
1970 Cadillac Sedan DeVille
1970 four door Convertible w/Cadillac Warranty

Jeff Rosansky CLC #28373

Yah,
I need to get one of those manuals too.  With Scott's help I have pretty much come to the conclusion that I need a transducer.  I found a used one but no luck.  Still looking but all I need for it to do is cool for now. 
Jeff
Jeff Rosansky
CLC #28373
1970 Coupe DeVille (Big Red)
1955 Series 62 (Baby Blue)
Dad's new 1979 Coupe DeVille

bcroe

I don't have a book, but I'll tell how I got on top of my 79 Eldo CC. 
The first problem is the CC is automatic; it has a mind of its own.  I managed to
identify the variable elements; I disconnected them (temp sensors) and instead
connected my own manual reostat This allowed me to set it into any specific mode
that needed attention. 

The factory manual shows the exact state of each air valve, etc for each mode. 
With the mode set, its not too bad to track down what is or isn't happening. 

Some people say to look for certain faults.  Fine, but if one of those isn't it, you
are up the creek.  Knowing what state things should be in, THEN tracking down
why that isn't so, will always lead you to the issue.  Bruce Roe

TJ Hopland

I like the idea of substituting sensors with something like a pot or resistor.   I bet the fancy factory test machine had a couple dials on it that did just that.   Make it think its either hot or cold in the car and see what happens. 
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

"Cadillac Kid" Greg Surfas 15364

Sounds like you are on the right track to me.  A thorough understanding of exactly what is going on rather than a "shot-gun" approach to symptoms is the proper way to diagnose ANY mechanical/electrical device. Yes the sensors or the entire sensor string can be "simulated with simple rheostats (I have built one from radio shack parts) and you can represent any inside or outside conditions to "present" to the programmer's input.
Greg Surfas
Cadillac Kid-Greg Surfas
Director Modified Chapter CLC
CLC #15364
66 Coupe deVille (now gone to the UK)
72 Eldo Cpe  (now cruising the sands in Quatar)
73 Coupe deVille
75 Coupe deElegance
76 Coupe deVille
79 Coupe de ville with "Paris" (pick up) option and 472 motor
514 inch motor now in '73-

Scot Minesinger

Yes, agree:  You must know what is going on and not throw parts at it.  Have found screws thru sensor wires making heat never come on in 1966 and 65 Caddies done by sound system jockeys that do a horrible sloppy job.  They even rout the wires through the back seat spring structure so you have to disconnect speaker wires and re-route properly to remove back seat to work on convertible top pump.  Unfortunately the programmers in every 74 - 76 Caddy I have worked on has been bad, so I'm inclined to judge them harshly.
Fairfax Station, VA  22039 (Washington DC Sub)
1970 Cadillac DeVille Convertible
1970 Cadillac Sedan DeVille
1970 four door Convertible w/Cadillac Warranty

bcroe

My 79 had a 3 pin connector leading to the variable sensors.  I unplugged them and
connected my test box, which is marked with each mode.  Don't know that every CC
has such a connector, but the wires can be found & connectorized if needed.  The box
and the circuit are on my PHOTOBUCKET, user bcroe.  Bruce Roe

TJ Hopland

My system has got extra wacky now.   Had to unplug the ac compressor to keep from the thing freezing me out of the car.   I wonder if the sudden deterioration had anything to do with the extra cold winter we had.   Sent my money to Tim for his book so I can do some testing and get things figured out. 
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