I have a 2000 E320 wagon with a V6, automatic and 160K miles. I've had the car for a year and a half and I've had no issues other than electrical grimlins. (and the sudden breakage of the window cable pulley)
I've never heard the electric fan run on the radiator. The engine never runs hot according to the guage and the needle usually sits about horizontal on the gauge. When sitting in traffic, the needle might go up near the next tic mark on the guage, but never any higher.
Since I've never heard the fan run, even in 95 degree weather, I thought I would check the fan itself by adding 12 volts to the harness connectors to see if the fan ran. It did, and ran fast.
I checked the large 50 size fuse under the hood and it was good.
What else could I check and is this normal???

 

Hi, This is quite normal, you will find that the running temp should be horizontal, maybe slightly. I don't know what the temperature is in the US, but in Australia that would be about 80-90 degrees If i recall. The fan does not really need to come on and only will if the motor rises above the normal running temperature. Also, if you turn on the air con, after some time with the air con on, the fan will turn on, sometimes for a short time, sometimes longer. Hope that helps.