Auxillary cooling fan not working on low speed

My auxillary cooling fan not working on low speed when A/C is turned on

The high speed works jumpered directly when using the temp sensor on the rad. The low speed does not work when jumpered.

I have checked the fan resistor and it is at .8 ohms- I think this OK.

I have checked the continuity of the low speed wire - OK

I removed the low speed relay and there is no power when I check terminal 30on the low speed relay.

Any ideas?

Thanks

Check out normal speed relay K21 in the auxillary relay box in the engine compartment. EDIT, sorry didn't notice that you had already checked the normal speed relay.

I also have the same problem on my MB... still can't figure out why. All relays are good. Fan will run at low speed when I manually trigger it... I changed all sensors... I know it is the pressure sensor on the accumulator to trigger the fan and that is brand new... There got to be another trigger because when my car is starting to overheat, the aux fan is supposed to trigger high...