question about side vent

Mr.Baca · 09-04-2009, 09:53 AM

so i have my first mr2 and its just parked in my driveway because my license is suspended

so i cant move it well i turn on my car every 3 days and let it warm up till the thermostat is half way but my side vent fan never turns on is that normal does it only turn on when it is realy hot like when driving for a while

curvesrgood · 09-04-2009, 10:35 AM

I don't hear mine kick on very often... I'm guessing the car does have to be pretty hot before it kicks in. I've noticed a few times in the past few weeks that if I've driven the car very hard and bring it home to park it I hear the fan running. Otherwise I don't think I ever hear it kick on. Anybody else?

muffinman · 09-04-2009, 10:40 AM

the vent fan has an engine bay sensor and has nothing to do with coolant temp. i have never seen mine come on by itself. if you want to test it just unplug the sensor (big white plug at rear of head ) with the car running and it should kick right on.

mr2_jake · 09-04-2009, 01:04 PM

Mine comes on quite frequently, but only for a few seconds. If I remember correctly, when the engine bay temp reaches somewhere around 120 it kicks on till it lowers to around 100, then shuts back off.

toyotaspeed90 · 09-04-2009, 05:15 PM

Key just needs to be set to "on" for it to turn on.

when I had my 7age in my 87 I heard it kick on all the time.... I had an unshielded header, though.

YellowJacket · 09-05-2009, 12:01 PM

Quote:

Originally Posted by toyotaspeed90

Key just needs to be set to "on" for it to turn on.

when I had my 7age in my 87 I heard it kick on all the time.... I had an unshielded header, though.

Not true. This fan is triggered by a sensor in the engine bay when the ambient temperature reaches 168 degrees for more than 10 minutes I believe, and it is controlled by a fan computer behind the ecu in the trunk. If your fan is on all the time, you need to replace your fan computer. It is bad. When you turn you car on the engine fan should NOT come on if everything is working properly. If it does come on, then its in failsafe mode from a failed component, most likely the fan computer.

As mentioned you can pull the wire from the sensor in the engine bay to test the system. If it doesnt turn on after you unplug it, you have another problem and can test the fan itself by running 12v to it to confirm the fan itself turns and wiring works there.

If it does turn on when you unplug the fan wire from your sensor but doesnt turn on after Sitting idle for a while after a very spirited drive then you either have a relay, sensor (not as likely), or a fan computer malfunction (very likely). The sensor is testable with an ohm meter and some hot water but like I said its the least likely to fail in my opinion. The fan computer failing is probably the main cause of fail-safe (always on with ignition).

The fan is not loud, but you can hear it, and it draws a good amount of air (and dust) from outside to inside, so you should definitely be able to tell its on audibly if you are listening for it and by the feel of the air induction with your hand or hold a piece of paper against it and it will suck it to the car... cigarette would work if you smoke.

The haynes manual or BGB states all this a bit more eloquently, but thats the deal paraphrased.

side note: The cooling fan dummy light in the dash is ONLY for this fan. It lights up when the fan SHOULD trigger on but does not. It has nothing to do with the liquid cooling system.

mr2_jake · 09-05-2009, 12:08 PM

Hmm, mine comes on when key is in "on" position. I usually run my 2 hard on the curvy race track I call my driveway, and when I park and shut her down the fan remains on, regardless of key position, for a few seconds.

toyotaspeed90 · 09-05-2009, 09:03 PM

Quote:

Originally Posted by YellowJacket

Not true. This fan is triggered by a sensor in the engine bay when the ambient temperature reaches 168 degrees for more than 10 minutes I believe, and it is controlled by a fan computer behind the ecu in the trunk. If your fan is on all the time, you need to replace your fan computer. It is bad. When you turn you car on the engine fan should NOT come on if everything is working properly. If it does come on, then its in failsafe mode from a failed component, most likely the fan computer.

As mentioned you can pull the wire from the sensor in the engine bay to test the system. If it doesnt turn on after you unplug it, you have another problem and can test the fan itself by running 12v to it to confirm the fan itself turns and wiring works there.

If it does turn on when you unplug the fan wire from your sensor but doesnt turn on after Sitting idle for a while after a very spirited drive then you either have a relay, sensor (not as likely), or a fan computer malfunction (very likely). The sensor is testable with an ohm meter and some hot water but like I said its the least likely to fail in my opinion. The fan computer failing is probably the main cause of fail-safe (always on with ignition).

The fan is not loud, but you can hear it, and it draws a good amount of air (and dust) from outside to inside, so you should definitely be able to tell its on audibly if you are listening for it and by the feel of the air induction with your hand or hold a piece of paper against it and it will suck it to the car... cigarette would work if you smoke.

The haynes manual or BGB states all this a bit more eloquently, but thats the deal paraphrased.

side note: The cooling fan dummy light in the dash is ONLY for this fan. It lights up when the fan SHOULD trigger on but does not. It has nothing to do with the liquid cooling system.

the relay is turned on by the COR...... which turns on when the key is set to on, not necessarily when the engine is running. It turns on when the temp reaches where it should.

the sensor is not a switch style sensor.... strangely enough, even though the technology was there for a switch style thermistors, this one isn't.... it's a true thermistor (I know this because I had to use one as an intake sensor on a JDM gze). Also, I doubt there's a timer built in as there's no need for one.

so, if you had read what I said correctly.... it can turn on when the key is set to on... I did NOT mention engine bay temp.

Further, if you all want to go on about this.... there is little that the side vent does at above 35mph..... aerodynamics of the car make it somewhat useless.... the lower plastic covers (and the vents in the engine lid) are meant for air movement to go from under the car to up through the engine bay. So, for anyone wanting to add a fan to the engine lid for whatever reason, wire it as a puller.

YellowJacket · 09-07-2009, 07:21 PM

Quote:

Originally Posted by toyotaspeed90

the relay is turned on by the COR...... which turns on when the key is set to on, not necessarily when the engine is running. It turns on when the temp reaches where it should.

the sensor is not a switch style sensor.... strangely enough, even though the technology was there for a switch style thermistors, this one isn't.... it's a true thermistor (I know this because I had to use one as an intake sensor on a JDM gze). Also, I doubt there's a timer built in as there's no need for one.

so, if you had read what I said correctly.... it can turn on when the key is set to on... I did NOT mention engine bay temp.

Further, if you all want to go on about this.... there is little that the side vent does at above 35mph..... aerodynamics of the car make it somewhat useless.... the lower plastic covers (and the vents in the engine lid) are meant for air movement to go from under the car to up through the engine bay. So, for anyone wanting to add a fan to the engine lid for whatever reason, wire it as a puller.

Yeah, I get the whole useless above 35mph thing.. worth mentioning though... I always thought that was a cooling fan more for if you are sitting in slow traffic or at idle on a hot day anyway... I wouldnt imagine it would ever get over 158 above 35 mph in the engine bay anyway with the airflow there.

and Yeah, I understand now what you are saying when you mean it will "turn on." I was interpreting you to mean all you have to do is turn your key on, and the fan runs (all the time). Which is a failsafe situation. But it sounds like you mean, the circuit is on.

I couldnt remember about the accuracy of my "timer" statement, and took a quick look at a BGB and all it says is that the fan comes on for a sec during ignition (as you indicated) but immediately shuts off if the sensor reads under 129 degrees and turns on if its reading over 158 (not 168) degrees.

As far as the timer part, the BGB doesnt state anything that I found easily, but I recall getting that info (right or wrong) from another forum (dont believe everything you read right) and as the cooling fan computer behind the ecu is what monitors the sensor/thermistor... could it not act as the "timer" and not trigger the fan on unless it gets a constant reading for a specific duration?

Makes me want to have some extra status indicator lights... rad fan , engine fan , and tvis.

toyotaspeed90 · 09-08-2009, 03:12 PM

yes.....

on track days, if the side vent fan is on I will turn the engine off but keep the fan running and the engine lid open when in the pits.

YellowJacket · 09-08-2009, 09:47 PM

Quote:

Originally Posted by toyotaspeed90

yes.....

on track days, if the side vent fan is on I will turn the engine off but keep the fan running and the engine lid open when in the pits.

Which is accomplished by turning the key to accessory position to kill the engine but keep the circuit open so the fan runs, correct? Pretty cool. (literally)

toyotaspeed90 · 09-09-2009, 05:07 PM

yes.... typically (again, at the time it was a running rich 7a on a header w/o shields... aka gets hot there) it would run for about 3 min and shut off.

YellowJacket · 09-10-2009, 12:41 PM

Quote:

Originally Posted by toyotaspeed90

yes.... typically (again, at the time it was a running rich 7a on a header w/o shields... aka gets hot there) it would run for about 3 min and shut off.

But is the fan really necessary or effective or just helpful in that situation?

I wonder how long it would have taken for the engine to cool on its own to the same 128 degrees needed to turn the fan off....

and then the second question, is, in the scenario where the engine does take X minutes longer to cool down on its own to 128, does it really matter that the engine took X more minutes to reach the same 128 degrees?

I still surmise the side vent fan becomes the most effective and useful at long idle or in slow traffic jams on the interstate in the sweltering heat...

09-04-2009, 09:53 AM	#1 (permalink)
Mr.Baca No Skills Join Date: Jun 2009 Posts: 36 Thanks: 4 Thanked 0 Times in 0 Posts iTrader Rating: (0/0% )	question about side vent so i have my first mr2 and its just parked in my driveway because my license is suspended so i cant move it well i turn on my car every 3 days and let it warm up till the thermostat is half way but my side vent fan never turns on is that normal does it only turn on when it is realy hot like when driving for a while

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09-04-2009, 10:35 AM	#2 (permalink)
curvesrgood three mk1's Join Date: Feb 2006 Location: NC Posts: 345 Thanks: 7 Thanked 26 Times in 21 Posts iTrader Rating: (0/0% )	I don't hear mine kick on very often... I'm guessing the car does have to be pretty hot before it kicks in. I've noticed a few times in the past few weeks that if I've driven the car very hard and bring it home to park it I hear the fan running. Otherwise I don't think I ever hear it kick on. Anybody else?

09-04-2009, 10:40 AM	#3 (permalink)
muffinman Brain Surgeon Join Date: Jan 2008 Location: Ft. Lauderdale Posts: 1,797 Thanks: 24 Thanked 102 Times in 99 Posts My Google Map iTrader Rating: (1/100% )	the vent fan has an engine bay sensor and has nothing to do with coolant temp. i have never seen mine come on by itself. if you want to test it just unplug the sensor (big white plug at rear of head ) with the car running and it should kick right on.

09-04-2009, 01:04 PM	#4 (permalink)
mr2_jake Many skills... Join Date: Sep 2009 Location: Billings, MT Posts: 83 Thanks: 0 Thanked 7 Times in 7 Posts iTrader Rating: (0/0% )	Mine comes on quite frequently, but only for a few seconds. If I remember correctly, when the engine bay temp reaches somewhere around 120 it kicks on till it lowers to around 100, then shuts back off.

09-04-2009, 05:15 PM	#5 (permalink)
toyotaspeed90 No Skills Join Date: Jun 2006 Location: Bellingham, WA Posts: 422 Thanks: 0 Thanked 32 Times in 32 Posts My Google Map iTrader Rating: (0/0% )	Key just needs to be set to "on" for it to turn on. when I had my 7age in my 87 I heard it kick on all the time.... I had an unshielded header, though.

09-05-2009, 12:08 PM	#7 (permalink)
mr2_jake Many skills... Join Date: Sep 2009 Location: Billings, MT Posts: 83 Thanks: 0 Thanked 7 Times in 7 Posts iTrader Rating: (0/0% )	Hmm, mine comes on when key is in "on" position. I usually run my 2 hard on the curvy race track I call my driveway, and when I park and shut her down the fan remains on, regardless of key position, for a few seconds.

09-08-2009, 03:12 PM	#10 (permalink)
toyotaspeed90 No Skills Join Date: Jun 2006 Location: Bellingham, WA Posts: 422 Thanks: 0 Thanked 32 Times in 32 Posts My Google Map iTrader Rating: (0/0% )	yes..... on track days, if the side vent fan is on I will turn the engine off but keep the fan running and the engine lid open when in the pits.

09-09-2009, 05:07 PM	#12 (permalink)
toyotaspeed90 No Skills Join Date: Jun 2006 Location: Bellingham, WA Posts: 422 Thanks: 0 Thanked 32 Times in 32 Posts My Google Map iTrader Rating: (0/0% )	yes.... typically (again, at the time it was a running rich 7a on a header w/o shields... aka gets hot there) it would run for about 3 min and shut off.