We have a problem b/c when I noticed the passenger side one wasn't spinning today, I moved it and it just spinned without any hesitation with the push of my hand, while the other one was going full force... so even though in parallel only one is working

While in these episodes the a/c stops cooling, which obviously is tied to eng temp...

1984 300d Turbo 135k
Engine Hot, Turn Off Engine, Move Fan By Hand If Loose Replace
Fan Clutch $160.00

The fan motor itself is at fault [ probably brushes, as you have verified the bearings are not locked up by hand spinning ]...
The a/c has a high pressure switch that will cut the compressor in the event that the high side pressure has reached a danger zone caused by high thermal load conditions, which is exactly what a non operating aux. fan will create. These two fans are activated by high coolant temp for the high speed and a/c high side pressure for the low speed. Either activation requires both fans to run at the same time, regardless of which system is being called for.
Fan motor should be replaced.

I had a similar problem on a 1991 300e 4matic in the UK, 205,000 miles

When I bought the car it would overheat quickly, and max out when stationary. A new thermostat (very cheap and quick to fit) cured that problem immediately.

During the diagnosis of this I noticed that neither of my 2 electric auxillary fans worked. I managed to get one slowly back into life by tapping the centre spindle lightly with a small hammer. Following this I drilled a small hole into the plastic cowl which covers the centre of the fan motor and filled this with WD40 spray lubricant using the straw that comes with it. Shorting out the temp sender I let the fan spin for 5 mins to free it self up. You may wish to silicone up the small hole once all is well.

However this method hasn't worked on both fans, but is worth a try as a temporary fix. I think the power lead may have become detatched from the other, and it's not easy to get access to.

In any event with the new thermostat the car doesn't get hot enough to turn the fans on (105 degrees I think) and my aircon is out of gas which is the other trigger for turning them on.

When did the problem start, right after the new water pump or later?

__________________
Michael

1988 300 SL (5 Speed)
1994 E320 Wagon
1997 C230

Fan motor? So I don't have to replace the whol fan assembly?

Problem started? hmm, I guess recently.....few wks.

Some mentioned fan clutch, I can check that as well, but no qiuestion I have to fix the non operational fan first.

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1995 E320 smoke silver / parchment

just that side..

http://catalog.eautopartscatalog.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=catalog.mercedesshop&baseurl=http://catalog.peachparts.com/&cookieid=1M30LAGSC1NJ00QFW3&year=1995&make=MB&model=E-320-001&category=G&part=Auxiliary+Fan+Assembly


..Used to be able to get just the motor , but looks like they have the fan assemb now...

I would avoid using the AC in stop/go traffic until the fan assembly has been replaced. High temperatures are not only bad for the engine but they are worse for electronics/wiring. As it is, the electronics in these cars are hanging in there by a thread

If one fan has gone bad, the other one is probably on the way out as well. You can tilt the radiator to get the fan assembly out. Should take maybe 30 mins.

The fans on my car were running slow and intermitently blowing out the fuse.

These fans have been refered to as "garbage cans" on these forums, as they were a bandage, to update the W124 without changing the architecture.

Above 25 mph, the W124 does not need any cooling fan under normal conditions.

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Zafar
94 E320 58000 Miles