My 2008 C30 2.4 non turbo rad fan is not working, it has the relay incorporated in the fan motor with the 3 pin plug 3 wires = 12V/ Ground and small signal wire..


First test: Tried it with the AC on and the AC compressor cycles on and off, sprayed the Ac condenser with water and the AC will cool fine, compressor stays engaged but the cooling fan will not run.


Second Test : let the car idle and watched the temp rise to 240 F and the fan never kicked on.


Third test: Unplugged the connecter at the Fan and check for power with my meter 12- 13 Volts with the ignition on or off.


Fourth Test: Ignition in the off position. hand spins free by hand.


Fifth Test: with the engine running Fan connecter unplugged used my meter on the lowest DC volt setting and monitored the small signal wire to ground. I did see change in the reading with engine cold, Ac on, and Engine up to temperature. I realized using a volt meter is not the way to do it but I wanted to see if there was any change in the signal.


Sixth test: Sent 12v power using a battery direct to the fan motor after the relay and the fan spins.


Seventh test: Got a used fan from the auto wrecker installed it still no better. Yes I know I could have got anther bad fan I should have bought a new one but was trying to save money.


Questions I Have for you experts out there,


1) What type of signal does the ECM send to the fan relay? is it ohms?
2) Is there any way of tricking the relay to simulate the ECM signal.


Thank you in advance JD