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72chevy4x4
07-05-2010, 04:08 PM
for those of who have two condensor / AC fans, MB part numbers reveal in some way they are different. The size/blade design appears to be identical, but the CFM (cubic feet / minute) moved or the speed may be different. The control / power circuitry is located at the bottom engine side of the radiator.

their being two fans, it is clear one fan comes on when the AC is turned on. when does the second fan turn on?

72chevy4x4
07-25-2010, 09:04 AM
ttt

Chandlerazman
07-26-2010, 05:01 AM
I had mine (2nd fan) turn on only in extreme heat of 110 or over. When it came on it was a variable speed and it was loud at full bore. Definately know when that bastard is running!

cedarsanctum
07-27-2010, 11:31 PM
We've just returned from a 2,875 mile trip to Colorado and back through Grand Teton and Yellowstone, traveling many days in temps of 105F. I heard what i would assume is both fans coming on many times. It is audible even traveling at 65+ MPH with the stereo playing. At slow speeds it is just loud. I've never been able to determine which or even how many of them come on. It's usually when we're moving, and by the time i get stopped i have forgotten about it. Not important enough.
What i know is this vehicle kept going hour after hour in this heat, and we were comfortable the whole time (except when i forgot that the light on means AC is OFF, stupid system). When these vans run right, they are great!
Jef

72chevy4x4
07-28-2010, 01:37 AM
except when i forgot that the light on means AC is OFF, stupid system

I've considered installing a blue led to in the hvac panel to indicate when the AC is on...so backwards. Wonder if the guys driving E320's and S500's have this issue.

Aqua Puttana
07-28-2010, 01:55 AM
I guess I've been mistaken in saying that the electric fans aren't effective when the Sprinter is at highway speeds.

I still wonder how efficient they are. Given that the air is being rammed into the radiator at speed, the viscous clutch fan (if hot) should be at full on, and the aux (electric) fan blades are spaced so far apart (to provide less resistance to flow if they aren't running?) it surprises me that they would help much when they turn on at highway speeds. I may be missing something.

Can anyone comment if the coolant temperature drops immediately when the electric fans kick on at highway speeds or is it a slow, gradual decline until they finally turn off again? Just curious. vic

72chevy4x4
07-28-2010, 02:06 AM
I can't reply to AP's post but think that the fact that the radiator's can't keep cool enough with air flow at high highway speeds is intriguing aerodynamic property of the Sprinter.

Diamondsea
07-28-2010, 02:28 PM
Ram air through the front at highway speeds has to have someplace to exit. The engine space is so stuffed full of machinery how much area is there for the hot air to get through and exit downwards? Is there high pressure under the van or low pressure suction to help pull air through? Is it possible that as the speed increases the pressure underneath actually increases? Do we have any aeronautical engineers on this forum?

photoadjuster
07-28-2010, 02:47 PM
Diamond,

Just tape some tuffs of yard over, under and around the engine compartment. Then have a friend, a very good friend, hold you out the window by the ankles. Then, if all goes well, you can report back to us.

That's what we do with the homebuilt aircraft we build.

cedarsanctum
07-28-2010, 07:58 PM
That's what we do with the homebuilt aircraft we build.

That's funny, do you wear a parachute? Sky is softer than pavement.

I watched the temp readout in the dash but it wasn't able to display anything useful about temperature changes in the engine. It stayed pretty steady in one place while the fans came on and off. It could have been they each came on at different times and created different levels of sound, but i wasn't paying that much attention. Next trip into 105F temps i'll connect the iPhone monitoring app and read the direct readouts. Oh yeah, there will be no more trips like that. ;)

Jef

Aqua Puttana
07-29-2010, 12:21 PM
Ram air through the front at highway speeds has to have someplace to exit. The engine space is so stuffed full of machinery how much area is there for the hot air to get through and exit downwards? Is there high pressure under the van or low pressure suction to help pull air through? Is it possible that as the speed increases the pressure underneath actually increases? Do we have any aeronautical engineers on this forum?
Diamondsea,
Good comments. Even given the close space, I would still think the mechanical fan would be enough to move the air while at highway speeds. That said, comments from someone using experience or data would be nice to have as you suggested. vic


...
Then have a friend, a very good friend, hold you out the window by the ankles. Then, if all goes well, you can report back to us.

...

Sounds more like a job you'd assign to an ex-wife than a good friend.:bounce: vic