what controls the fans?
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From: Houston Tx
what controls the fans?
I got the idle working pretty well but in the process I noticed the temp got up to 216 idling and no fans are running. The back fan runs when I turn the AC on, the front one doesn't do anything at all. Are they controlled by a temp sensor someplace? when are they supposed to come on and which ones are supposed to come on? Arlon
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From: Athens AL
C7 of the Year - Unmodified Finalist 2021
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Put the year of the car in the post.
Main fan in 86 is controlled by the ECM, it wont come on until 228F unless the AC is on, in which case it cycles based on pressures. It also shuts off when you are cruising at speed.
The aux fan in front of the radiator only comes on at 238F, and is controlled only by a temperature switch in the head.
Main fan in 86 is controlled by the ECM, it wont come on until 228F unless the AC is on, in which case it cycles based on pressures. It also shuts off when you are cruising at speed.
The aux fan in front of the radiator only comes on at 238F, and is controlled only by a temperature switch in the head.
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From: One day you're a Comet...the next day you're dust... Arkansas
Aux. fan temp sensor is in the head between and below plugs 1 and 3 on my 1989. Look there on yours. There should be a connection from the wiring harness on the drivers side.
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From: One day you're a Comet...the next day you're dust... Arkansas
You can replace the sensor in the heads with a 200* on 185* off switch. You would probably want to put a 180* thermostat in if you did that to give the sensor some "headroom".
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From: Santa Maria CA
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From: Houston Tx
Thanks for that info. I do like the idea of going to the faster on switch though. Here in houston traffic/heat, by the time the fan comes on it just seems to take a long time for the engine to start shedding the heat. I'm also getting some detonation when the temps get high. In the 200 range I'm not getting any noticeable detonation. Above 225 I can hear the clatter for a few seconds..
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From: Rochester PA
Aux.fan Sensor Removal
I have an '89 w/no aux. fan. Is the main fan sensor between 6 & 8? Also, I can not get the plug for the aux. fan out. I tried most everything. Bought some bar stock, and it twisted it into a pretzel. Someone suggested heat. Anyone else w/this problem? Any advice would be much appreciated.
Rich K
Rich K
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From: The Top of Utah
The main fan is controlled by the ECM. The ECT sensor is in the front of the intake manifold. According to MY parts book, in 1985 through 1989, the hole between the #6 and #8 spark plugs, is for the temperature sending unit for the dash gauge. The auxilliery fan switch would go in the same hole on the other side of the engine, which would put it (or the pipe plug) between the #1 and #3 spark plugs.
RACE ON!!!
RACE ON!!!
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From: All great change begins at the dinner table Ronald Reagan
Originally Posted by CFI-EFI
The main fan is controlled by the ECM. The ECT sensor is in the front of the intake manifold. According to MY parts book, in 1985 through 1989, the hole between the #6 and #8 spark plugs, is for the temperature sending unit for the dash gauge. The auxilliery fan switch would go in the same hole on the other side of the engine, which would put it (or the pipe plug) between the #1 and #3 spark plugs.
RACE ON!!!
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I don't have a sensor there, it's plugged.
I have a temp sensor in the front of the engine, with a double pronged connector.
The fan switch sensor between #1 & #3.
I know these are correct, I went thru several stores before I was corrected.
CFI, I'm not doubting you, I'm wondering why I don't have a sensor there, could not find a wire for a sensor. I've seen them there. I heard that one sensor is for the ECM, one for the dash guage, some were for both. But, mine heats up, still indicates low temp for coolant. (There's another sensor on the radiator = Low Coolant?
My Main fan is not working. Still working on that ...
Last edited by redvtt; Jul 31, 2006 at 03:40 PM.
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From: One day you're a Comet...the next day you're dust... Arkansas
I have an '89, the aux fan sensor is between and below plugs 1 and 3. It has a two wire jumper splitting out of the drivers side wiring harness. Are you sure you have an aux. fan?
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From: Houston Tx
Originally Posted by BADDUCK
That sensor for the 200* aux fan is $14.95 at Midamerica.
Found it.. Thanks..
Last edited by Arlon; Jul 31, 2006 at 04:42 PM.
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From: Santa Maria CA
Originally Posted by Arlon
do you have a link? Best I stumbled across was about $50 "hypertech" switch.
I have it one on my '86 single fan and it works great.
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From: Rochester PA
I was asking for suggestions about getting that stupid, odd ball plug out, so I can screw the aux. fan sensor in there. Like I said above, it won't budge. Anyone ever have one so stubborn? Would localized heat help? Or would I be taking a chance of screwing up an expensive alum. head? Anyone?
Rich K
Rich K
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From: Santa Maria CA
Originally Posted by thirdtimevetteowner
I was asking for suggestions about getting that stupid, odd ball plug out, so I can screw the aux. fan sensor in there. Like I said above, it won't budge. Anyone ever have one so stubborn? Would localized heat help? Or would I be taking a chance of screwing up an expensive alum. head? Anyone?
Rich K
Rich K
If no, grind down an old 1/4 short extension to 8mm size. (An 8mm wrench will just go over it on each side all around. )
I found that nothing else fit the hole short of this. Even real snap on pipe plug sockets for square holes where not made for that size.