My 1995 E320 is overheating because the aux fans in front of the radiator seem to be turning off when they should be staying on. Most of the time they stay off and in this 100+ degree weather in Durham, North Carolina that is making me run way too hot. I have had the issue before where the blade fuse in the relay blows and they just stop working period. This time the fuse is good and I was very surprised to see the fans both turning on while I had it in the driveway idling. Then they turned off which it was pretty clear they should not of. Is there a thermostat or switch somewhere that I can test? When the fans are running they appear to be running fine and they spin freely when not running. Is there a way I can jump to the fan(s) to make sure that they are ok and start looking at switches or relays?

Thanks very much,
Jim Lee
1995 E320 wagon