E30 wiring question - aux fan high speed relay

My Aux fan is not working on the the high speed. My first test was to jumper the green black(+12vdc) to Brown/ Black at the temp sensor on the radiator. The high speed did not work (low speed worked fine). I verieid the fan works on both speeds by putting voltage across both wires at the fan. I have verified coninuity all the way back to fuse #18 (30A). I swapped relays K5 & K6 and then went as far as veirfying the relay worked on the bench...it did. I give you all that back ground info just to ask........is the energizing side of the relay coil get its voltage from the temp sensor (brown / black wire)? My guess is yes. If so, is there anything in between? My Bently manual does not show this diagram.

I found the answer to my question. The black / brown wire coming from the high speed connection at the radiator sensor was broken behind the drivers side head light. Once I repaired this I can now jumper the connector @ the sensor and the high speed fan comes on!!! My problem is still not fixed. The car runs right past normal operating temp all the way to HOT and the high speed fan does not come on. (this is with A/C on & stuck in traffic) I replaced the sensor & the car still over heats. I tested the sensor in "boiling water" and both high and low work. When I put the new sensor on the car neither high or low indicate a short when the temp is getting hot. When I jumper the sensor connector so the high speed fan comes on, the temperature gores back to normal range. So....next question...is it possible there is any air pocket in my radiator or the coolant is not circulating in this chamber? Antifreeze comes out when I remove the sensor.