2001 xk8 My ac is cold but the radiator fans will not turn on and the high side pressure goes so high that the compressor kicks off. Can I pull the connector on the pressure switch , apply battery power to terminal LF57-3 to activate the fan?

I already checked the function of the radiator fan control relay module.

 

Also to see if the fan will work from engine coolant temperature sensor, will the fan turn on if I just pull connector or do I short the wires?

 

You can not apply battery power to the pressure switch connector! But you can try and ground it.
The pressure switch gets switched ground on terminal 4 from the ignition switch and sends a grounded signal to the ECM. The ECM then sends ground to the Fan relays.

 

I t looks like I could apply 12 v to LF57-3 which is what would happen when pressure reaches 12 bar. Am I reading that incorrectly ?

 

Yes you are. As I said; the pressure switch is not fed by +12V but ground from the ignition switch!

 

okay, I did not race that signal back to ignition switch. so if I just ground LF57-3 is that sufficient to signal the relay fan to operate

 

so I pulled the connector. and there is a lot of corrosion in the plug

where does that come from? is this the source of my refrigerant leak? all
refrigerant leaked out over 2 days

 

the corrosion eroded one tab completely

 

so I took apart the connector. and I will replace the contacts