Is my ML trying too hard to keep cool?
05-21-2003, 08:38 PM
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Mercedes-Benz
Is my ML trying too hard to keep cool?
Hey dave, When I drive my ML for about 10 min the thermostat reaches like a hair over 80 and then stay pegged there. However a loud fan seems to come on the whole time the car is on and it seems to slow the car down. It is kind of annoying and has done this since last summer that I have noticed. I keep the A/C on year round, not sure if that makes a difference. I noticed our C-class temp is between 90 and 100 and my friends ML500 is also between 90 and 100 in normal driving. What is going on here?
05-25-2003, 12:53 PM
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The auxilliary fan temp sensor is bad making it go on too early. Check the sensor with a meter to see when it kicks on(at what temp) and replace if needed.
05-25-2003, 04:34 PM
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YOU MAY HAVE A THEMOSTAT STUCK OPEN WHICH IS WHY THE TEMP NEVER GOES UP. ACCORDING TO MBZ THE TEMP IS USUALLY 87C AND UP. IT IS STAMPED ON THE BACK OF THE THEMOSTAT.
I BELIEVE THE FAN GOES ON WHEN THE AC IS ON.
I BELIEVE THE FAN GOES ON WHEN THE AC IS ON.
05-26-2003, 03:32 PM
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2016 BMW Z4 sDrive35i M Sport
My C 280 usually stays a hair above 80, and my fans come on al lot. But it usually stays constant except on really hot days it'll climb up there.
05-27-2003, 07:55 PM
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It seems that there is something wrong with the electrical circuit of the cooling system. Electric failures in the system make the fan run all the time. Because the fan runs when it should not run (yet), the engine does not reach normal operating temperature.
Because you "feel" it slows the car down, I think maybe a fuse is blown in the back of the fuse box (not between the other fuses, but separate under the backside of the "all activity module") that also feeds other electrical systems such as motor management.
Because you "feel" it slows the car down, I think maybe a fuse is blown in the back of the fuse box (not between the other fuses, but separate under the backside of the "all activity module") that also feeds other electrical systems such as motor management.
05-28-2003, 01:31 AM
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Mercedes-Benz
Originally posted by patrick
It seems that there is something wrong with the electrical circuit of the cooling system. Electric failures in the system make the fan run all the time. Because the fan runs when it should not run (yet), the engine does not reach normal operating temperature.
Because you "feel" it slows the car down, I think maybe a fuse is blown in the back of the fuse box (not between the other fuses, but separate under the backside of the "all activity module") that also feeds other electrical systems such as motor management.
It seems that there is something wrong with the electrical circuit of the cooling system. Electric failures in the system make the fan run all the time. Because the fan runs when it should not run (yet), the engine does not reach normal operating temperature.
Because you "feel" it slows the car down, I think maybe a fuse is blown in the back of the fuse box (not between the other fuses, but separate under the backside of the "all activity module") that also feeds other electrical systems such as motor management.
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05-28-2003, 06:05 AM
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Originally posted by AlBoston
...I took it to the dealer about this before, they said it was normal...
...I took it to the dealer about this before, they said it was normal...
That does not sound normal to me!
I am just not that sure about that "hidden" fuse because most of the ML's we have in our workshop are diesels and I do not know by heart if it is there at gasoline engines. Because it fuses all "engine add-on"-systems like EGR (and the regulation of the cooling fan) and so on it can be there too.
(But it is definitly not where all the other fuses are)
05-28-2003, 03:51 PM
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2003 s500 sport
Wait,
Is the fan on even if the AC is off at this temp? When the AC is on the fan goes on automatically all the time. And the 80+ temp is just right? Why would you want 90-100.
Is the fan on even if the AC is off at this temp? When the AC is on the fan goes on automatically all the time. And the 80+ temp is just right? Why would you want 90-100.
05-28-2003, 05:15 PM
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The thermostat (is that English?) should regulate cooling temp at about 87 degrees C.
The fan is controlled in different steps. When you hear the fan working it is running at one of the highest steps (or highest step). This is only so when the engine temp reaches a certain temp (what is not so), or the A/C pressure becomes too high.
The fan should not turn that fast just because the A/C is on.
The fan is controlled in different steps. When you hear the fan working it is running at one of the highest steps (or highest step). This is only so when the engine temp reaches a certain temp (what is not so), or the A/C pressure becomes too high.
The fan should not turn that fast just because the A/C is on.
06-30-2004, 10:24 AM
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'05 A4 1.8TQM6
I believe for most, if not all MB's, the normal temp range is usually right around 80c and between 80c-90c.
On really hot days (90 degrees+) w/ AC on, probably close to 100c even.
On really hot days (90 degrees+) w/ AC on, probably close to 100c even.
