There is a way to jumper the aux fan to test it, on the receiver drier- but which two wires?
I got a used fan, which didn't come with a plastic end plug, so when I cannibalized the old plastic end plug(they snap apart) I had to guess which wire end was supposed to go where. I don't think I have ever seen that fan move. Thanks

__________________
'02 BMW 325i
'85 300D 450k
'93 190E 2.6 170k(killed by tree)
'08 Ducati Hypermotard 1100S 6k
'06 Ducati S2R800 14k(sold)

If you've still got the wires bare or the plug unhooked ...12 volts D.C.

If not ...the two wires connected to the A.C. high pressure switch ,when
jumped (to each other) start the fan.[unplug the connection from the H.P.
switch and "jumper" the two connections together]

And make sure your hands are out of the fan's way. I got nicked pretty bad by mine a year ago when I was putzing around in front of the car while it was idling/hot out, all the sudden on roars the fan and one of the blades smacked my poor knuckle!! It hurt! They're quite powerful!

__________________
-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)