You have to remove the ashtray and part of the lower dash to get the radio out.

Before the spring season will start in May, I want to make sure that all my cars are in top notch condition until then.
The radio on my 78 suddenly died last summer. I was driving the car and the radio and 8-track and CB worked flawlessly. It had great sound and everything worked.
Suddenly, when I wanted to turn the volume down a little bit, the antenna retracted, and the radio went off completely and I could not turn it on again. I also could no longer operate the power antenna.
When I was home I discovered a blown fuse and replaced it, but it immediately blew again when I wanted to turn the radio back on.

I took the radio out now, and measured the power source, and I can clearly see that there is a problem somewhere inside the radio.
It looks like the power source is defective.

My friend Steve who is really good in repairing older radios offered to have a look at it. Unfortunately I cant fix this myself, as I have no clue how this could be repaired, or what could be defective…
Its great to have such good and competent friends who can fix such things.
In a very short time Steve found out what was wrong with the radio. One of the many condensators on the radio got dry over the years and caused a short. Steve replaced the broken condesator and even replaced all the other old ones with new ones to make sure that the radio will last for a long time.
I can´t thank Steve enough for fixing the radio for me. It is very important for me to know that it works again - I hate when things do not work properly on a Cadillac.
When I installed the radio back into the car, it came back to life, but the FM functionality did no longer work, and it was stuck in AM mode. 8 track and CB worked perfectly, but I could not switch to FM mode.
So Steve was so kind to disassemble the radio once again, and found the problem with a disengaged spring which could no longer activate the AM/FM switch.

The radio is out of the car - it's the one with 8-track and CB - the most expensive one available in 1978. You can see the replaced condensers on top of the radio.
This bigger condenser was the cause for the trouble - it got dry inside and caused a short. The others were exchanged as well as a precautionary measure.
The back side of the radio.
You have to remove the ash tray assembly to get the radio out

The radio works again and is back in the dash. 8-track and CB work perfectly as well.

The GM demo tape which came with the car sounds amazingly good. Love the sound.

While I was working on the car I finally repaired the glove box light switch which had a problem since I got the car. I got a new switch from Arizona Vintage Parts and it now works perfectly again.

The glove box light is back in working order.


I also replaced the cars original hot water valve, which had a leak at the vacuum diaphragm and could not close any longer.
I found a perfectly working NOS replacement on ebay for it, as the one I got from Rockauto before looked completely different.

The new hot water valve in place.


The 67 Eldorado´s Automatic Climate Control System is back in working order

Today I managed to solve the issue with the partly non working Automatic Climate Control of my 1967 Eldorado. As described in the entries below, the blower would only come on in full heat modes when the car was accelerating. The AC of the Eldorado is very similar to the one from the DeVille btw.
I suspected a vacuum leak somewhere in the system. Troubleshooting began with going through all the vacuum hoses. I replaced some which were a little worn out at the connectors. I also cut off the ends of most hoses, as they were all becoming a little loose during the last 40 years. I then plugged them in again.
Not much did change though.
When I came to the hose of the hot water valve and the delay relay, I had the first success. At least the blower motor would stay on in all “Auto” modes, even when the car was idling - but would still go off in “Fog” and “Ice”. I then suspected a leak in the power servo or in the dash controller. So I installed the power servo from my 67 DeVille where everything works perfectly, to be able to rule out any problems. Nothing changed though - the blower would still come on and off depending on the throttle position.

I then soon found the culprit of the whole issue - it was the master vacuum switch - which seems to have a problem with the internal electric switch. As I had a spare one around I installed it - and voilá - everything worked as it should. It always looked good when I checked it before.
I´m very happy that everything is back in working order. The only thing which I still have to repair is the fast idle diaphragm which completely dried out and is no longer functioning. Fortunately I do have a spare 429 engine in the garage from where I can grab and use this part - so I will repair it soon.
I then need a new condenser which is already on the way across the Atlantic coming from Old Auto Air.
By the way - Cadillactim has an excellent trouble shooting guide for the ACC on his website.

The evaporator had to be replaced as well along with the heater core. This is a pretty big task as you can see on the pictures below. You even have to remove the hood to get access to the whole unit. The fiberglass AC enclosure had to be repaired at my car as well as the previous owner tried to repair the evaporator and missed a screw and made a tear into the enclosure. The restoration shop repaired this professionally and it looks like new now.

The best troubleshooting guide for 1967 and 1968 Cadillac´s Automatic Climate Control Systems I got today from Gary Sisk - owner of a 1968 Cadillac.
This is a very easy to follow explanation which will save you a lot of time and you do not even need any special tools.
It was written by Lynn Nicholls and can be found on Stampies Cadillac page - here is the direct link to it.

Below you can find some pictures of my system:

The whole AC unit has to be removed to get access to the evaporator and heater core... The slight surface rust that showed up where the gaskets were, was removed as well of course...
The big hole on the left is where the blower motor is installed.

This is where the AC box usually is installed

You can see how much has be removed just to get to the evaporator and heater core...

I discovered the first issue at the hot water valve
The hoses around the time relay delay were leaking a little bit
For testing purposes I hung a spare master vacuum switch into the car - this solved the problem
The old fast idle diaphragm was leaking and brittle and was replaced with a better one...
1967 Cadillac Automatic Climate Control Vacuum diagram
The 1967 Cadillac Automatic Climate Control Vacuum Schematic from the shop manual -
1968 is almost identical BTW... Click on the image for a larger view!

Here is a video about the Master Switch that a gentleman posted on youtube