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Getting H V & A C worhing on '74 ELDO

Started by Viator Trudeau, August 21, 2014, 01:19:30 PM

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Viator Trudeau

Am using Tim's manual.   Just started.  Vac. control bar in programmer pulls in all the way as soon as engine starts W/ dash lever in any position.  Cant find the 3.5 to 5.5 volts W/ any where when bar is all out or in???  Am tracing all vac. lines from engine to dash and programmer.  A C is cold W/ Programmer laying on floor.   Need to look more, looks like transducer??   

V. Trudeau

cadillactim

Make sure you have battery voltage at yellow wire going into programmer. If no voltage is being sent to transducer, programmer will go into full heat mode.

Tim
Tim Groves

Scot Minesinger

The wiring harness that plugs into the transducer is poor quality and can be a problem.  Some times when you plug it back on programmer the wires slip out of the black connector and instead of connecting to spade they back out - check for that too.  This has happened to me 50% of the time when I repair these, and of course the first one took a while to find. 
Fairfax Station, VA  22039 (Washington DC Sub)
1970 Cadillac DeVille Convertible
1970 Cadillac Sedan DeVille
1970 four door Convertible w/Cadillac Warranty

Viator Trudeau

Thanks to Tim & Scot for the help on my "74 ELDO A C.   I have battery voltage (13.5) @ yellow wire on connector, contacts are all solid, do not slide back.

V.Trudeau  #8697

Scot Minesinger

In fixing a dozen or so of these, only one had a programmer that was good and it was a 30k original car.  Likely a rebuilt programmer (includes transducer) is required if it is original.
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

Viator,
Before you condemn ANY parts check to be sure all the sensors are connected and not "open" (burned out). Frequently when
the dash cover is removed the in car sensor is not fully re connected.  Check the electrical connections at the control unit (dash control), as well as the ambient sensor on the heater/fan box under the hood.
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-

Viator Trudeau

Scot:  my programmer is original. Vac. motor will hold vac. for days.  Going to look for a rebuilt soon, will inspect to be sure.  Maybe individual pieces are available.

V. Trudeau   #8697

Scot Minesinger

Greg is right of course run through the diagnosis process on your car to be sure that the programmer is bad, just cast a scanted eye on it because that usually is the bad part.  Cadillac Tim in Iva, SC (google) sells rebuilt units for reasonable prices, he may sell you individual components, but I would buy the whole thing.  Yes check dash sensors if dash has ben apart.  One time on repairing a climate control system discovered a screw thru wire to sensor (grounding it) that an after market radio installer did (it was fun finding that).

One sign that the programmer was sure to be bad to me at least was when fan would only operate in high mode.
Fairfax Station, VA  22039 (Washington DC Sub)
1970 Cadillac DeVille Convertible
1970 Cadillac Sedan DeVille
1970 four door Convertible w/Cadillac Warranty