Mercedes Repair Questions? Ask a Mechanic for Answers ASAP
If the switch is in the top hose it will switch the fan on regardless of vehicle speed and therefore take no account of natural air movement/cooling.
Surely the bottom hose is the more logical position as the fan will only be switched on if the radiator has not done enough without help?
Okay I accept what you say, the fan I am using is 2 speed unit, I will probably put a lower temp sensor in the top hose for the low speed and a higher temp sensor in the bottom hose for the faster fan speed.
The original viscous coupling is not an on/off switch I believe it slips less/drives more as temp of air through radiator rises, therefore reacting to the situation rather than just overcooling.
Thanks for your thoughts.