ac light flashing, consistently after 3 seconds

2008 4 cylinder tacoma, ac light flashes after 3 seconds every time i turn on ac, never been intermittent. i replaced the compressor with reman unit, had system evacuated before and professionally recharged, tried 3 different lock up sensors, tested one - ok, magnetic clutch relay is fine, replaced ac amplifier with new toyota. seems like everything that is listed on posts here, but none corrected problem. ac works fine when i use a jumper wire in place of the clutch relay, but very inconvenient to install every time i need ac on. ive wanted to install a switch instead of using a jumper wire, but not sure where wiring needs to be grounded to turn on clutch, except at relay, but difficult to add a wire to relay recepticle where relay needs to be plugged in place. if anyone has any ideas on what else would cause this constant problem, or can advise me what wire in wiring harness near amplifier or relay box, can be grounded to turn clutch on would be very helpful.

 

What did you do with the Original Toyota sensor.
It has often been an issue with aftermarket sensors not working properly.
Install an OEM Sensor and it will probably work.

 

In my experience only the OEM lock sensor will work

 

Have you checked circuit integrity between the Lock Sensor and A/C Amplifier?

You don't want to just add a switch to force the compressor on because that would defeat both the high pressure cutout and evaporator freezup protections.