OK so I dropped a screwdriver into one of my aux fans and didn't know it. Took if for a ride after I rebuilt turbo and opened the hood to check for leaks. Smelt that burning electrical smell we all know. The driver side fan not longer works. The passenger side does. Are these controlled together as a unit? I suspect I have a burned out fan, but was hoping for a separate control or fuse. Any luck?

Are they single speed?

Do you know what CFM they are?

If fan is toast, do you sugest a OEM remplacement? Thanks.

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1990 300d 2.5 new to me.

Fans are wired in parellel.
The speed is controlled by a resistor circuit, not the motor itself.

Wrecking yard...OE fan only ...others won't hack it.

Both run together.

Needed for good low speed a/c performance.

Needed for coolant overheat.

I run my 1992 300e with no belt driven fan. Drove to Florida last week...no problem....I run Evans Coolant....zero pressure cooling system.....both fans kick in at under 100 C when idling and run at low speed while a/c on....drops to just above 80C under way.

Trip = 2800 miles@ 24.7 mpg.

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[http://languageandgrammar.com/2008/01/14/youve-got-problems-not-issues/ ]

"A liberal is someone who feels they owe a great debt to their fellow man, which debt he proposes to pay off with your money."

Thanks for the info. I'm searching for an assemby as I type. Does this "resister" vary? In other words, does it vary the speed of the fans?

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1990 300d 2.5 new to me.

Two speed resistor..iirc ....tapped for high and low.
Located on inner fender behind head lamp?....iirc.


.

__________________
[http://languageandgrammar.com/2008/01/14/youve-got-problems-not-issues/ ]

"A liberal is someone who feels they owe a great debt to their fellow man, which debt he proposes to pay off with your money."

The resistor [ R15] is only used in the Low Fan circuit..the High Fan circuit does not use the Resistor..allowing full battery voltage to fan motors.

The Low Fan circuit is actually called the Pre-resistor circuit.
So, to answer your question..there are two speeds-- High/Low. And they both have independent circuits [ seperate relays,sesnors, fuses, etc.] They share the same fan motors only
The low fan circuit is triggered by the a/c system high side pressure switch and has the Resistor in series with the fans..that is how low speed is accomplished.
The High fan circuit is triggered by the Engine coolant temp sensor/thermistor @ 105C and is direct battery voltage, no resistor used for that circuit.

AUX Fans. DO they both come on or just one.

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Hi,
I have a 1997 s420 and when I turn on my AC, only one aux fan comes on(driver side). Is that normal? I also noticed yesterday that my low level coolant light was on but the tank had plenty of fluid. Is this problem related.
thanks for your reply.

Both fans.

Coolant level sensor faulty.
Replace windshield water level sensor if replacing the coolant level sensor does not fix the warning light .

Zeesh.........this post is MONTHS old !
.

__________________
[http://languageandgrammar.com/2008/01/14/youve-got-problems-not-issues/ ]

"A liberal is someone who feels they owe a great debt to their fellow man, which debt he proposes to pay off with your money."

They work in unison..
Try turning the dead one by hand...leaves and stuff may be binding it. If it is free , then next time the other one comes on, give that one a hand flip and see if it starts..if it does , replace it. If it doesn't , check the wireing at it's plug..

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A Dalton

I also have a 97 E420. My dual aux fans get sticky frquently. I try to unstick them by hand rotation and it works sometime but not always. Is this a straight forward easy replacement? Thanks.

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85 300CD Signal Red/Tan sold
83 300D Manganese Brown 109K
97 E420 Midnight Blue 197K sold
98 BMW 328i Vert White 100K, sold
95 BMW 525i White 125K, sold
93 BMW 525iT Red 193K, sold
95 E320 Green Wagon 125K, sold
94 E320 White 127K, sold
85 300SD 156K Grey (Annie), sold
84 300D Lapis Blue 170K (Judy), sold
99 ML 320 Black (lease), 1998 C230 White (lease)
00 Honda S2000 Red (lease)
86 Mercedes 300E (sold)
84 Porsche 911 Red (sold), 1965 Porsche 911 White (sold)

Completely different animal.

On yours the left fan drives the right side via a small belt. They are not hard to replace.

If you want to test operation, turn key to pos 2 and on your CCU press and hold rest and ec for 10-12 secs. Fans will run full power.

__________________
Terry Allison
N. Calif. & Boca Chica, Panama

09' E320 Bluetec 77k (USA)
09' Hyundai Santa Fe Diesel 48k (S.A.)

Terry, my fan's not working so can I just replace the single electric motored fan assembly which drives the passive fan assembly rather than buy the entire dual fan assembly?

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85 300CD Signal Red/Tan sold
83 300D Manganese Brown 109K
97 E420 Midnight Blue 197K sold
98 BMW 328i Vert White 100K, sold
95 BMW 525i White 125K, sold
93 BMW 525iT Red 193K, sold
95 E320 Green Wagon 125K, sold
94 E320 White 127K, sold
85 300SD 156K Grey (Annie), sold
84 300D Lapis Blue 170K (Judy), sold
99 ML 320 Black (lease), 1998 C230 White (lease)
00 Honda S2000 Red (lease)
86 Mercedes 300E (sold)
84 Porsche 911 Red (sold), 1965 Porsche 911 White (sold)

You'd beter look at yours, it may be different than my 99. Mine has two fans, one is a slave powered by the other.

http://www.detali.ru/cat/oem_mb2.asp?TP=1&F=210072%5F45P&M=119%2E980++++++119%2E985&GA=722%2E625&CT=F&cat=45P&SID=50&SGR=015&SGN=01

__________________
Terry Allison
N. Calif. & Boca Chica, Panama

09' E320 Bluetec 77k (USA)
09' Hyundai Santa Fe Diesel 48k (S.A.)