Author Topic: 1956 Cadillac A/C wiring diagram  (Read 141 times)

Offline Greg Simon

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  • Name: greg simon
1956 Cadillac A/C wiring diagram
« on: November 11, 2017, 04:29:28 PM »
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

Offline Bob Kielar

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Re: 1956 Cadillac A/C wiring diagram
« Reply #1 on: November 12, 2017, 11:29:21 AM »
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
« Last Edit: November 12, 2017, 11:41:22 AM by Bob Kielar »
Keep Cruzin
1955 Cadillac Fleetwood

Offline J. Gomez

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Re: 1956 Cadillac A/C wiring diagram
« Reply #2 on: November 12, 2017, 06:50:41 PM »
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

Time is irrelevant when you work on your classic car, eventually you will enjoy it..!

Re: 1956 Cadillac A/C wiring diagram
« Reply #3 on: November 13, 2017, 12:55:31 PM »
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

Offline lexi

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Re: 1956 Cadillac A/C wiring diagram
« Reply #4 on: November 13, 2017, 02:41:57 PM »
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
« Last Edit: November 13, 2017, 02:44:03 PM by lexi »

Re: 1956 Cadillac A/C wiring diagram
« Reply #5 on: November 13, 2017, 03:00:51 PM »
Without the AC running, the keyswitch won't get overly warm. 
Art Gardner


1955 S60 Fleetwood sedan

Offline lexi

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Re: 1956 Cadillac A/C wiring diagram
« Reply #6 on: November 13, 2017, 03:27:22 PM »
Art thanks. That is what I thought. Some warmth but not much. Clay/Lexi

Offline J. Gomez

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Re: 1956 Cadillac A/C wiring diagram
« Reply #7 on: November 13, 2017, 04:08:20 PM »
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

Time is irrelevant when you work on your classic car, eventually you will enjoy it..!

Offline lexi

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Re: 1956 Cadillac A/C wiring diagram
« Reply #8 on: November 13, 2017, 04:16:02 PM »
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
« Last Edit: November 13, 2017, 04:20:25 PM by lexi »