Fixing the 1978 Cadillac Eldorado´s ATC programmer. The AC works again.


An update to the article below can be found here as I had to repair the programmer again in May 2015:

The air-condition in my 1978 Biarritz did not work correctly. For some reason the system always stayed in full AC mode and no matter to where I put the temperature dial on the control head I could not get the heat on, no matter what I tried.
The shop manual is very helpful in trouble shooting the system. Its covered in the 1977 factory shop manual (FSM) as there were no changes made to the system in 1978.
It took me a while to fully understand how the system works - so I had to read the FSM multiple times to get the grip what is going on in the system.

First I inspected all the vacuum lines in the car to make sure that there was no leak anywhere, as the heating mode requires a very high vacuum at the vacuum motor in the controller.
All lines were in very good condition. I also checked the control head connections in the dash which were good as well.
I then suspected the vacuum motor in the programmer as it did not move. I removed the programmer from the car. You can access it from underneath the dash on the passenger side or even better if you remove the glove box lining through the glove box.
From there you only have to unscrew 5 screws, unplug the wires and the vacuum lines to get it out.

When I had it out of the car I checked the vacuum motor. I just sucked air through the hose and it moved and held vacuum perfectly.
The transducer or the amplifier in the programmer were most likely the problem.
When I checked the transducer which regulates the vacuum supply to the vacuum motor, I noticed that it seemed to not be connected to the electrical board as it should. I pressed it in, so that it made good contact with the board again and put the programmer back into the car and connected everything again.

***UPDATE 2015 - its not connected with pins but soldered to the circuit board - 3 of this soldering points were broken - the “repair“ I made here only temporarily worked. You have to check the soldering points for a permanent fix***

I started the car and the AC came back to life again immediately. I could see how the vacuum motor went through all the modes as it should according to the position of the temperature dial on the control head.
The build quality of the programmer obviously is not very good and the transducer somehow came loose causing the ATC to not work as it should. ***Update 2015 - it did no come loose but the soldering points broke***
After I tested everything I put the parts back together and can now enjoy a full working ATC in my 78 Biarritz again ;-)

The programmer as seen through the glove box with the connectors and the plastic case removed

The 1977 / 1978 Eldorado MK II Automatic Temperature Control Programmer

The transducer which caused the problem (the golden part with the single vacuum line going into it)

The transducer is connected to the electrical board through a couple of pins - it was not connected properly and somehow became loose over the years - that was why the system did not work.
***UPDATE 2015 - its not connected with pins but soldered to the circuit board - 3 of this soldering points were broken***

The vacuum checking relay and the electric connectors.

The vacuum power motor
from the 1977 FSM

Trouble shooting guide for when the system works in full AC mode only.

A color coordinated electrical schematic with annotations to describe the various functions of the system.


Detailing the paint of my 1978 Biarritz.

I continued to work on the 78 Biarritz during the last few weeks.
My goal is to make this mint car as good as it can get, while keeping everything as original as possible.
I´m really obsessed with cleanliness when it comes to cars... Everything has to be completely detailed and shining like new.
I completely cleaned the entire engine and gave it a good wash and afterwards applied some engine dressing.
I then removed some screws and small parts which were left unpainted by the factory, like some screws, the hood latch, some brackets and some other smaller parts. Of course these parts developed some slight surface rust during the last 36 years...
As I had no real rust dissolver at hand, I soaked the rusty parts in vinegar over night, which completely removed all the surface rust. I then gave these parts a coat of primer and painted them with Eastwood paint, which looks like bare metal.
With this method I can keep the rust away, while the parts still look original. Only if you look very closely you might see that these few parts are now painted...

I then started to bring the original single stage paint back to like new condition.
I used a couple of Meguiars compounds and polishes to make the paint as smooth as possible. I had to carefully wet sand some of the deeper scratches with 2000 grit paper. Be very careful when doing this as the single stage paint was applied in only VERY thin layers during the 70s.
The car now shows almost no more paint imperfections and the swirl marks are gone. The original paint looks like on a new car now and is extremely shiny. When the car is out in the sun its almost blinding.
I sealed the paint with Meguairs #16 wax.

I used a Meguiars DA polisher (G125) for the paint correction work - which is not really that good, but I would like to have a more powerful machine for the future like the Flex 3401 or the Rupes Bigfoot .

I used the procedure explained in the following video for my paint correction:

Download his description as PDF file here

This gentleman, Larry Kosilla, has a lot more awesome video tutorials for people who love detailing their cars. Check him out!

I also started detailing the interior of the car. I treated the leather with Gliptone Leather Conditioner - which is the best conditioner I have tried so far. It really makes the leather very soft.
I´ll have to steam clean the carpet once its really warm outside so that it can dry fast afterwards.

I also cleaned the undercarriage a little and removed some of the factory applied undercoating from components where it does not belong to, on which they sprayed it on very carelessly at the factory. Looks much better now.

The car really looks spectacular already - I´ll continue with the chrome and stainless steel trim now. It should be shining in fully glory for the 2014 season beginning in May and also be ready for various car shows, especially the Cadillac BIG Meet in August.

My weapons of choice came from the Meguiars dealer...
before and after cleaning
rusty bolts before and after cleaning
Soaking rusty parts in vinegar
Cleaning more rusty parts
with the rust removed
The Hood latch cleaned and painted with Eastwood Silver Cad Paint
The cleaned engine bay

The car after polishing the paint

the polished paint
very shiny
Besides the carpet - the interior is already perfectly clean. The original floor mat is under the aftermarket mats.
Cleaning the Vogue tires.
Clean paint and tires
Clean tires and perfect hubcaps
Before waxing

I really like this Meguiars wax. Its one of their cheapest but best waxes. A gentleman from Meguiars once told me that it is one of their oldest waxes, but contains a lot of carnauba wax, which makes it so good! Its also offering the best protection of their product range.

Here are some links to Meguiars products I like to use (link to german Amazon Shop):


1978 Cadillac Eldorado - defective door jamb switch repair.

I´m fully detailing the 78 Biarritz at the moment. During this I think I found the only non working gadget this car offers. The 78 Biarritz came with an automatic seat back release. When you open the door a solenoid engages and you can fold the seat back without pushing any button or lever to allow rear passengers to get in or out of the car. When you close the door again the seat lock engages and the seat back stays in position.

I also have the same system on my 1971 Lincoln Mark III where I had some problems as well in the past with a loose wire.

On the Biarritz the passenger side worked flawlessly, but on the drivers side the solenoid would not engage.
I started my search for the problem at the top of the two door jamb switches which is the one controlling this function.
When I wiggled it and pulled it out, I could hear the solenoid engage. So I knew that the problem must be with this switch.

Unfortunately it's not easily accessible. As I do not have the 1978 shop manual yet - it took me a while to figure out how to access it.
I managed to get to it through the lower dash and to uninstall it.
As it turned out it was slightly bent and did not make good contact once the door was opened.
I carefully bent it back straight - and after some trial and error it was back in working order.
It took me a good hour to fix this.

Now I´m back to cleaning the car to my standards, something that will probably take the whole winter...

The upper switch is controlling the seat back solenoid. (Picture was taken before cleaning the door jambs...)

The removed door jamb switch. When the door is closed no contact is made and the solenoids are not energized causing the seat back to be locked in position.
You can see that the switch was slightly bent - making no good contact.

When the door is open contact should be made and the solenoid should energize... The switch did no longer make a good contact though.

I had to remove the lower dash to access the cables on the rear of the door jamb switch through a tiny hole and disconnect the connector with a long nose plier...

I´m now in the long process of thoroughly cleaning the engine bay to look like new again...


The 1978 Eldorado Biarritz has arrived.

8 weeks ago this fantastic 1978 Eldorado Biarritz started its long journey across the Atlantic Ocean to Europe. The car was coming from Carrollton, TX.
You can read more about how I found it here.

This morning I got a call from the truck driver that he got lost in my town with his big truck. So I had to find him and guide him near to my home to unload the truck.
The 78 rode on top so all of the other cars had to get unloaded first.

The Biarritz was quite dirty after its long journey and probably saw snow for the very first time.
I drove it home the short distance from the parking lot and it absolutely drives like a new car. I thought the car had stalled - but the engine simple is so quiet and is running so well that you can't hear or feel it from the inside...
Also the transmission is shifting unnoticeably.

My little boy helped me washing the car upon its arrival at my garage, which was not an easy task with temperatures below freezing. Ice was forming on the car immediately...
Eventually I managed to get the dirt off, and the best 1970s car I have ever seen appeared. It's an absolute stunning car. The interior is like new, the paint is super nice with almost no flaws, and the chrome is mirror like in its appearance. The undercarriage is super clean and rust free, as it was coated when new. The trunk is looking like it was never used. All the weatherstripping is like new as well. The leather is soft and clean with no tears or sign of any wear. The engine bay is all original and unbelievably clean as well.
The car was equipped with most available options that were available in 1978 except the sun/astroroof, fuel monitor system and the heavy duty cooling system.. Everything else you could order in 1978 is there and works as it should. Also brand-new Vogue tires were installed just recently. The previous owners took extremely good care of this Eldorado.

My friend Tayfun came to visit to help me detail it and bring it to my standard of cleanliness. It will take another few days until we will be finished with it.
As everybody knows build quality was not exactly the best in the 70s - but I have seen other 70s cars with lower mileage which were not as good as this one. Looks like it was built during a motivated shift ;-)

I will add a 1978 Biarritz section to my website soon with lots of info and pictures - stay tuned!

I have to thank my friend Alex who made this purchase possible. Thanks a lot my friend - you made a dream come true. Condition wise this car is the best in my humble collection.

The first time I saw the car - the driver had to back up for half a mile as he has hit a dead end street...
The Biarritz rode on top
Little Elliot and me washing the car
Cleaning in freezing temperatures with my little son Elliot
Drying in the garage
After drying
Detailing with q-tips
Look at that perfect chrome
Mirror like chrome bumpers

perfect leather - before cleaning
My friend Tayfun helped cleaning the leather

After cleaning and conditioning the front seats
only 11k miles


A spectacular low mileage 1978 Cadillac Eldorado Biarritz is on its way to my garage!

One of the Cadillacs I always really liked is the last big Eldorado - the 1978 Biarritz!
Lots of collectors seemed to have thought alike in 1978, when the new downsized 1979 Eldorado was introduced, as they began storing the last big ones aside, and started to tuck them away in their air conditioned garages. Because of this, some of the 1978 Biarritzes survived in spectacular condition, like the car that is coming to my garage hopefully soon all the way from Carrollton, TX.

It was another Cadillac fan who sent me a link to an ebay auction just for my viewing pleasure. When I looked closer, I recognized that this triple yellow, fully loaded, super low mileage Biarritz seemed to be in spectacular condition and that it was very well cared for.
The car did not sell on ebay and so I contacted the seller for more information and suggested a price to him. He was a pleasure to deal with and a real car guy and collector, who answered all my questions and sent me lots of great information. The seller seems to be a great guy.
After a couple of days a deal was made…Luckily a friend borrowed me the money for the purchase of the car.

The car was now picked up from the seller in Texas and is on its long way to Austria into my garage.
The first leg of its journey is to Houston - then it will be transported in an enclosed truck to Florida where it will be loaded into a container before it crosses the Atlantic to Rotterdam.

Cant wait to see this Colonial yellow car in real life - its probably the best 78 Biarritz I ever saw and know of.

The car was loaded onto the truck in Carrollton, TX
Heading towards Austria
Short before pick up
Look at that clean untouched engine bay!
Low mileage!
What a beauty
Looks like nobody ever sat in these pillowy seats...