News:

Due to a technical issue, some recently uploaded pictures have been lost. We are investigating why this happened but the issue has been resolved so that future uploads should be safe.  You can also Modify your post (MORE...) and re-upload the pictures in your post.

Main Menu

1956 Cadillac A/C wiring diagram

Started by Greg Simon, November 11, 2017, 05:29:28 PM

Previous topic - Next topic

0 Members and 1 Guest are viewing this topic.

Greg Simon

Its been a while since posting anything but looking for assistance. I'm trying to figure out the wiring that goes to a/c control that is mounted under the dash. I have the manual, it gives me an idea  but not really sure what wires go where.  Any body have any detailed photos or diagrams?  thanks
gsimon

Bob Kielar

#1
I don't know if the 56 wiring is the same as a 55 but here is the wiring for the A/C on a 55.

Keep Cruzin,
Bob Kielar
Keep Cruzin
1955 Cadillac Fleetwood

J. Gomez

Gene,

The $10K question for you is; are you also looking at the connections under the dash, the engine compartment and the rear evaporator?

I do not have a picture handy of the A/C dash control, I need to take one and point the wiring setup on the control tomorrow.

Meanwhile here is the '56 I modified with the missing piece (NSS wiring) from the manual.

Bob,

The ’55 and ’56 are very close the only difference between them is the ’56 did not have the relay to operate the compressor clutch coil, and the ’55 did not have the evaporator freeze thermostat.
J. Gomez
CLC #23082

Caddy Wizard

This is a good time to mention that the wiring can get plenty hot!  The power for the fans is routed from the keyswitch to the AC controls under the dash, and from there on to the fan motors in the trunk.  No relay.  All of the power for the fans comes through a fairly skinny wire jumping off of the keyswitch.  In heavy use, the wire gets hot, as does the keyswitch and even the ignition key.  You will find that if you are running the AC for a good long while, when you go to remove the key, it is so hot that it will almost burn your fingers.  This often leads to premature failure of the keyswitch itself.
Art Gardner


1955 S60 Fleetwood sedan (now under resto -- has been in paint shop since June 2022!)
1955 S62 Coupe (future show car? 2/3 done)
1958 Eldo Seville (2/3 done)

Lexi

#4
Wow, I had no idea that would happen Art, (my AC is currently not operational). Something to look out for when I delve into my AC. One question though, Art if one is NOT using their AC, would it be 'normal' for a '56 Caddy after a period of use to experience any heat at the ignition switch/bezel/key-way area? Or would a warm to hot condition only be experienced if one was using the AC as you described? This is of course assuming that everything else is OK and the ignition switch itself is fine. Clay/Lexi

Caddy Wizard

Without the AC running, the keyswitch won't get overly warm. 
Art Gardner


1955 S60 Fleetwood sedan (now under resto -- has been in paint shop since June 2022!)
1955 S62 Coupe (future show car? 2/3 done)
1958 Eldo Seville (2/3 done)

Lexi

Art thanks. That is what I thought. Some warmth but not much. Clay/Lexi

J. Gomez

Clay,

The A/C power side is fused by a 25A from the ignition switch path, so potentially you could be close to the max give or take a few amps depending on the fan thermostat settings and the cycling of the A/C clutch.  :o

Also one has to take the age of the wiring and the condition of it and the peripherals pieces fans, rheostats etc. which could be bring the load higher.

As Art mention the ignition switch will take the burden on the A/C load and the rest of the electrical circuit’s load that would be active with the ignition on.   8)

Adding a relay to feed the A/C fuse from a main +12V source and energizing the relay coil from the ignition switch is one solution, here is one that I’ll be eventually be adding on mine as soon as I get back to my to-do list.   :P

Again, this would off-load the A/C load from the ignition switch the issue remains with the older wiring and condition of the peripherals feeding from it.  :(
J. Gomez
CLC #23082

Lexi

#8
Jose thanks. You guys never cease to amaze me with your facts and info. In the past I did have a warm to very warm key but since have determined that I did have an internally arcing ignition switch (which may have been aggravated by my car overcharging). I also had some bad wires. So yes, the age of the wiring I find is often a factor with these cars. Clay/Lexi