Like Lt. Columbo, I have just one more point. It appears the only other device fed from the ACC terminal is the parking brake light. If it comes on when the parking brake is set and the ignition switch is in RUN or ACC position, the fuse must be good. If not, maybe the fuse or bulb but is some evidence that fuse may have blown. The wire from the firewall grommet to the A/C clutch may have rubbed through, shorted out and blown the fuse.
The basic factory wiring diagram is not too clear on the a/c circuits but the A/C circuitry is better displayed on page 24-4 at: http://www.jholst.net/64-service-manual/air-conditioning.pdf . The blower is fed from the fuse labeled HEAT A/C. The A/C compressor clutch is fed from the fused circuit labeled ACC on the fuse block. Actuation of any HVAC control panel push button other than OFF will energize the blower circuit with speed determined by pushing or pulling on the combination temperature control lever/blower speed controller. If either the MAX COOL or FR COOL button is pushed in, +12V is sent to the clutch. There is no low-pressure cutoff switch. The electrical switching of the blower speeds and clutch activation are controlled by the push buttons and involve sliding plates that were lightly lubed 50 years ago and may not fully engage unless pushed in hard. To test the clutch portion of the switch, disconnect the wire to the clutch near it and measure Voltage from its terminal to ground. With the key in RUN or ACC position, pushing in either the MAX COOL or FR COOL buttons should provide the needed +12V at the connector near the compressor. The light blue wire from the dash switch to the clutch does not pass through the bulkhead connector but passes through the firewall at a separate location along with wires to the blower speed resistor on the firewall. The light blue wire then winds its way across the engine to the compressor clutch connector.
Best wishes on getting you’re A/C working. We would need it here in central California today.
BTW, “INC” club webmaster John Holst is recovering from a fall which broke his hip. Four Ti lag bolts were required to put Humpty Holst back together again. He has just entered another hospital for continuing care so he is out of pocket for a while. His personal website has the parts and service manuals for all letter cars plus a plethora of other information—much of it specific to the ‘64K. http://www.jholst.net Click on “Chrysler 300 Resources”. John farms in north-central Iowa and drives a white 360 HP 300K coupe his father bought new in Des Moines (with A/C & Auto Pilot). Best wishes to John for a full and speedy recovery.
John Holt's site is
He has the service manuals 1955-1965
and includes the wiring diagrams at
------ Original Message ------
To: "yahoogroups" <chrysler300@xxxxxxxxxxxxxxx>
Sent: 6/22/2016 1:12:37 PM
Subject: [Chrysler300] 300K wiring diagram
Posted by: "Rich Barber" <c300@xxxxxxx>
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