1999 Toyota Camry fan for cooling rad.

I think you are on the right circuit.

I suck at electrical, but will try to logic this out with you.

I think the circuit in question is the one highlighted.

We know the circuit on the A/c side wiorks and can activate the radiator fan motor. Since the a/c fan will only come on if the a/c is running...I believe.

I would next test the A/C single pressure switch.

KHLow2008 Pmed me with this info:

Customer did mention unplugging the fan switch would make the fans work. The problem is with the fan switch. Check if the correct switch has been installed and if the internal part of installed switch is clogged.

Toyota system grounds circuit and when circuit opens, the fan relay works the fans.

Recheck if there are any lack of coolant in system after switch changes.