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1995 E300D
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206 Posts
Discussion Starter #1
My 1994 E320 Coupe temp has been creeping up with A/C on and I notice the cooling fans not coming on. The Fans are good, I tested them.
Q: When are the electric cooling fans supposed to turn on?
Q: What controls the fans to turn on?


Im new to the petrol engine, any input will be much appreciated.

Thanks

Jetdude.
 

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W124 Moderator
86 190E 2.3L 16V, 2 95 320TE's, 02 S500
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12,670 Posts
The two auxiliary fans have low and high speeds. Low speed engages when the AC is on and they will cycle as needed. The high speed kicks in at approx 105c and will run until the temp drops to approx 95c.

There are fused (15amp/30amp) relay's for each speed in the fuse box. Additionally, there is a resistor located behind the left headlight. It the resistor is bad, the fans will not operate.

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Registered
1995 E300D
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206 Posts
Discussion Starter #3
OK, for sure the fans are not working on low speed with the A/C on.
I will check the fuses.

What does the big resistor do? Can I take it out of the system? and just connect the two leads together?

Jetdude.
 

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Premium Member
2003 G500, 2000 SL500, 1995 E320 Cabriolet, 1980 TR8
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1,047 Posts
What does the big resistor do? Can I take it out of the system? and just connect the two leads together? Jetdude.
The big resistor drops the voltage to the fan motors to cause them to turn at low speed. If you remove it permanently the fans will always turn at high speed. Temporarily bypassing the resistor is a good way to test if it is "open" and a cause of no low speed fan operation.
 
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