You should read this whole thread from the beginning b/c it tells about the relays.

But , here it is again
The relays are in the relay box behind the fuse box You need to take the 6 screws off to get to them.
There is a relay for the high fan [which you claim is a low fan, but isn't] .and that relay is triggered by the coolant sensor that you modified the cut-in point on. That is ONE CIRCUIT. [ HIGH FAN}
There is another relay [ in the same case] that is triggered by the pressure sw you are jumping. That relay brings 12v down to the resistor, which then drops the voltage to the same fan motors , but this time they are a LOW speed fan b/c of the resistor. This is the SECOND CIRCUIT [ LOW FAN}
The point being, if you jumper the high pressure sw, you have to jumper the wires before the sw , not the wires coming out of the switch.. When you jumper these wires , the relay should CLICK.. IF it does not , then the problem is on the primary side of the relay circuit..if it does click, then you know that the relay is pulling in the contactors for the LOAD side of the relay, which should feed the 12v to the Resistor. That load side has a fuse .
IF the relay clicks and you still have no 12v at resistor, you have a fuse out or a bad relay.
You have brought 12v down to the resistor manually by-passing the relay and the fans came on, but the thing you want to do with that test is to bring the 12v to the single wire side of the resistor..That will test the resistor..if you brought 12v to the other side of the resistor, you have simple by-passed the resistor and verified nothing about the low fan circuit.
In essence, the true test is to bring 12v down to each side of the Resistor..[ one at a time]... on one side you should have High Fan, [ this will be the 2 wire side of R] on the other you should have LOW fan.. [ that will be the single wire side of R ] That will verify resistor and fan speeds
If you do finally get low fan w/high pressure sw jumper, do not condemn the sw..The problem on that condition is low refrigerant not allowing high pressure sw activation b/c it never reaches cut-in pressure.
Try those test and don't post back top terminal ,bottom temrinal, picture etc .
...that means nothing to me as I am working off a schematic. Give me a wire color or terminal #