What controls the???? - Benzworld.org

mr.xpowerseller · 10-25-2007, 03:02 PM

front auxiliary cooling fans on a 90 300SE? Mine appear to be stuck-on. Whenever the ignition is on, the fans are on. They don't over cool the car, but they might with the new rad/flushed cooling system (which is going-in tomorrow).

Is it the:
1.) Radiator Fan Controller/Resistor Your Parts Search Returned 1 Part(s)
2.) Radiator Fan Relay Your Parts Search Returned 1 Part(s)
3.) Radiator/Auxiliary Fan Switch; Blue Insulator with 2 Prong Connector; 130 Degree C Your Parts Search Returned 1 Part(s)
4.) Thermostat; 87 Degree C Your Parts Search Returned 1 Part(s)

I'm guessing #1, but I don't know.

Thanks!

NordRhein · 10-25-2007, 03:35 PM

They will not "overcool" the car. Temperature regulation is done by the thermostat. Either the coolant temp sensor switch is stuck "on" or a prior owner jumpered the circuit somewhere to help the A/C.

markusfmeyer · 10-25-2007, 05:15 PM

Good place to see if its "jumpered" is the receiver/dryer for the ac. See if there are two pins on the side that don't have wires on them, and instead those two wires are "spliced" or jumpered together. That's one possibility.

mr.xpowerseller · 10-25-2007, 07:13 PM

I'll check tomorrow. If it isn't jumped, then what would be exact cause (coolant temp sensor as said above) or should I just leave it be as it won't hurt anything?

mr.xpowerseller · 10-26-2007, 02:55 PM

Car is off at shop and won't returned until replacement parts come in on Monday or Tuesday, so I cannot check.

If it is jumped or otherwise messed up, should I just leave it be always-on?

**cyberdyne** · 10-26-2007, 03:09 PM

With your warm climate in Florida, I do not think it would hurt to have them on all the time, however you might as well get it fixed and have the car turn them on automatically. That should save wear-'n'-tear on the fans.

- Steve

jhodg5ck · 10-26-2007, 04:22 PM

Most likely your coolant temp or AC pressure switch has wonked out.

Start unplugging what not and it will make itself known

Jonathan

brandon671 · 10-26-2007, 04:26 PM

also if you got this car from a previous owner , they sell connections that will keep your fans on the entire ride, my father did it to his 140 and the engine never breaks 100 now.