wow am confused. In lay man terms please explain what i should do again. thank you.
A couple of possibilities...
As the A/C clutch is engaged and disenaged a HUGE electrical SPIKE hits the 12 VDC eelctrical system. That spike has been know to cause on-board engine ECU's to execute the wrong instruction stream.
With the A/C on the airflow into the engine compartment will be substantially HOTTER then otherwise so any solid state device sensitive to heat to be intermittent of fail.
You can alleviate a bit of this last effect by making the A/C substantially more efficient thereby less heating of the radiator and engine compartment via the A/C condensor airflow.
To do so use MAX, 65F, cooling, recirculate mode, and the lowest blower speed that will maintain your comfort level.
MAX COOLING...?? Counter-intuitive, right..??
Not actually.
MAX cooling bypasses the Lexus climate control's REHEAT/REMIX airflow path allowing fewer cycles of the a/c compressor. Better FE too. You can improve the A/C efficiency even more by disconnecting the reheat/remix servomotor actuation cable from the hot water flow valve (top/center of the firewall in the engine compartment) and tying the valve into the shutoff position.