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Old 07-29-2009, 06:34 AM   #1
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Engine rear passenger side blower fan.

At what temp should this fan kick on? I have heard the front fans on while the rear is not running. It took being low on coolant and the red light flashing to get all three on. Is there a way to check this rera fans operation without expensive tools?
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Old 07-29-2009, 09:48 AM   #2
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IIRC if the Engine compartment temperature reaches 158 F the fan will come on.
It's about $300 for a new Blower Motor Assembly.
...
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Old 07-29-2009, 12:47 PM   #3
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There is no set temp when the engine bay exhaust fan comes on. It is controlled by the DME which uses a number of variables - coolant temp, charge temp, ambient temp, etc. to activate the fan. If your fan went on, there nothing wrong.

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Old 07-29-2009, 12:55 PM   #4
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Related question: When I've been driving my Box ('01S) for awhile, I've noticed that often times if I come to a stop the engine bay exhaust fan is not on. I'll shut the car down, run into the store (or whatever), come back a few minutes later and restart the car. At that point, the fan comes on.

Is this normal? I.e., if it's hot enough for the fan to kick in after I restart the car, wouldn't it surely have been that hot when I rolled to a stop??
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Old 07-29-2009, 01:10 PM   #5
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Quote:
Originally Posted by Frodo
Related question: When I've been driving my Box ('01S) for awhile, I've noticed that often times if I come to a stop the engine bay exhaust fan is not on. I'll shut the car down, run into the store (or whatever), come back a few minutes later and restart the car. At that point, the fan comes on.

Is this normal? I.e., if it's hot enough for the fan to kick in after I restart the car, wouldn't it surely have been that hot when I rolled to a stop??

Not really. When the car is in motion, air flowing along the underside is picked up by the two diverters and directed through the engine bay and out the pass side vent maintaining a cooler temp.

But, once you stop the car (and the airflow), the engine bay temp increases beyond the threshold determined by the DME and the fan acitivates.

Another issue with these fans is the relay (#8 in the trunk relay panel). If the relay is intermittent, this too can cause an issue.

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Old 07-30-2009, 08:26 AM   #6
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2x

Another contributing factor, the block no longer has water coursing through it so instead of heat being carried away and dissipating through the rads, it dissipates through the block and into the engine compartment.

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Old 07-30-2009, 06:49 PM   #7
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Now why didn't I think of that??
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Old 08-02-2009, 06:48 AM   #8
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Quote:
Originally Posted by kabel
IIRC if the Engine compartment temperature reaches 158 F the fan will come on.
It's about $300 for a new Blower Motor Assembly.
...
Just read in the Bently Boxster manual that fans come on at two temps.
Low speed @206.2F or when AC is on

High speed @215.6F or AC switch closed.
This is substansially different than 158 degrees.

They are not clear between their coverage of the front fans and the single rear pass side engine blower fan however.
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Old 08-02-2009, 08:12 AM   #9
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Quote:
Originally Posted by bustingear
Just read in the Bently Boxster manual that fans come on at two temps.
Low speed @206.2F or when AC is on

High speed @215.6F or AC switch closed.
This is substansially different than 158 degrees.

They are not clear between their coverage of the front fans and the single rear pass side engine blower fan however.
Yes, but the fans they are referring to are the radiator fans, not the engine bay fan, which has only one speed and triggers by the DME............
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Old 11-01-2010, 08:35 AM   #10
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TEMP light

Well guys i am on my third waterpump and third serpentine belt. This time the pully let go but the beraing was fine. I chose to buy a LASSO this time and hope my troubles are over. I also found that the parts store are showing the wrong belt size. This is for the Dayton application. I had to take it up manually. Theromostat replaced 12 months ago.

Now to my current problem.
New waterpump installed.
Car burped properly.
New belt installed.
Temp normal and not showing hot.
Coolant not down but red light still flashing.
This morning I turned around after 10 miles and got back home. It was 25 degrees outside and the engine blower fan kicked on even when the temp guage said normal temp and the motor was OFF. What gives??? Relay, resistor???
I must also mention that the car did overheat this last time prior to replacing the waterpump.


Last edited by bustingear; 11-01-2010 at 08:41 AM.
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