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When I turn on my A/C, naturally the compressor engages.

When I turn off my A/C, the compressor does not disengage. Instead, it continues cycling until the engine is shut off, at which point it then disengages.

I am wondering if this behavior is an anomoly with my particular 1968 Toronado, or is this built into the 1968 Toronado's DNA?

Thank you,

Dave:

The easiest was to isolate this 'problem':

1) With the engine off, disconnect the electrical connector from the compressor clutch. Then reconnect but don't fully seat it. You want the connector to make electrical contact but allow removal while the engine is running & the clutch is applied...
2) Start the engine & turn on the A/C. Observe that the compressor clutch has applied.
3) Carefully pull the connector away from the clutch. Watch out for all moving parts...!
4) If the clutch releases, the 'problem' is in the electrical side of the A/C controls. If the clutch remains applied, the clutch is bad. It can be replaced without removing the compressor or discharging the refrigerant.

Keep us posted,

Paul

Hello Paul
The description as to why the AC compressor stays engaged after the off button is pushed or one switches to vent or heat, has to do with the way it is wired. Though your premise may apply to third generation AC units it is not so with 66-70 units and maybe later.
Once the AC is engage through the compressor relay the relays (hold circuit) stationed on the ignition side of the relay maintains power until the ignition is turned off. Don't know the reasoning behind this but that's way it was done at that time.
Later AC unit cycled on and off during use it was tough clutches but better for fuel consumption. The advent of rotary compressors provided of smother and quieter operation as well as better suited on /off cycling over the piston style.

Thank you Paul and Bill.