minimum voltage to run A/C

LOTS of bad, incorrect, information here, throughout the thread...

ken white wrote:
Should a motor ever be operated at lower than rated voltage?

The motor's load may be considered fixed, so the same work (or
power/energy delivered) is performed when operated.

No, the A/C compressor motor's load changes, increases, as head pressure rises. Turn off the A/C while the compressor is cycling, turn it back on quickly, the motor likely will not restart. The motor's internal HEAT sensitive CB will begin cycling on and off until the head pressure declines enough to allow the motor to restart. Or the house CB pops..

When the motor's input voltage is low, the input current draw must increase in an effort to perform the same work.

YES!

This increased current draw causes increased internal heating and reduced motor efficiency, which overheats the windings and core and can cause premature failure.

NO! P=IE, POWER (WATTS) = AMPS times VOLTAGE, reduce the voltage and increase the current, POWER doesn't change,....

But PF, Power Factor does.. The increase in current flow results partially from low power factor, the load begins to look more inductive than resistive. So, yes, current flow increases, but since that current flow is now "more" out of phase with the applied voltage, apparent power (derived strictly from voltage and current flow measurements) is greater than ACTUAL power consumption.

Example: Connect a high value bi-polar capacitor directly across the 115 volt AC line. A measure of power, current times voltage, will indicate power consumption when there is virtually NONE!

So, never operate any motor below its minimum voltage specifications or it will fail early.

Malarkey, not desirable, but the more critical issue is whether or not the compressor motor starts reliably each and every time without the internal self-resetting CB "popping".