A/C blower intermittent

Our A/C first would not turn off, after replacing the resistor on the blower/evaporator box it would turn off, however the blower would cycle on and off every few minutes. After replacing the relay in engine compartment fuse box the A/C system seemed to work, until I tried to max fan speed or consequently lower the temperature to below seventy two degrees. Both of these changes made the blower and A/C system stop intermittently. If I turn off the A/C system and back on auto it works ice cold and stays on, adjust the front fan to max or reduce temperature to sixties and it starts intermittent shutting off. The rear A/C setting have no effect and that works great, until the front system is faulted.

Would this be a pressure switch or bad blower motor overheating?

Still in the nineties in October here in sunny Florida. :)