85 cooling ?
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
Except in the winter, your fan is going to be on all the time!!! Your radiator cannot get rid of heat fast enough to maintain coolant temp below 180.
The only way to turn on the main fan at 180, is to install a chip programmed differently than stock. The stock chip turns the main fan on at 228F and off at 210F.
The only way to turn on the main fan at 180, is to install a chip programmed differently than stock. The stock chip turns the main fan on at 228F and off at 210F.
Team Owner
Joined: Sep 2001
Posts: 62,155
Likes: 1,731
From: Athens AL
C7 of the Year - Unmodified Finalist 2021
C4 of Year Finalist (performance mods) 2019
The fan setting is controlled in the ECM, it can only be changed there in the chip. 180 is too low, that fan will run all the time. It does not know or care what your thermostat is doing.
Unless you have wired in a switch to make it come on sooner and bypassed the ECM's control, thats the only way to change it.
160 is a choice I make based on climate and driving conditions, my site has my opinion on that.
Unless you have wired in a switch to make it come on sooner and bypassed the ECM's control, thats the only way to change it.
160 is a choice I make based on climate and driving conditions, my site has my opinion on that.
Thread Starter
Instructor
Joined: Dec 2004
Posts: 130
Likes: 0
From: Carlisle Pa.
Originally Posted by vader86
The fan setting is controlled in the ECM, it can only be changed there in the chip. 180 is too low, that fan will run all the time. It does not know or care what your thermostat is doing.
Unless you have wired in a switch to make it come on sooner and bypassed the ECM's control, thats the only way to change it.
160 is a choice I make based on climate and driving conditions, my site has my opinion on that.
Unless you have wired in a switch to make it come on sooner and bypassed the ECM's control, thats the only way to change it.
160 is a choice I make based on climate and driving conditions, my site has my opinion on that.
Ok i see ... the settings now are 160 fot the thermostat and 180 for fan
I want to put them back to stock.. I thought the temp sensor controlled when the fan came on.
Team Owner
Joined: Sep 2001
Posts: 62,155
Likes: 1,731
From: Athens AL
C7 of the Year - Unmodified Finalist 2021
C4 of Year Finalist (performance mods) 2019
temp sensor only tells the computer what the temp is, it does not directly control the fan unless someone has wired a switch off of it to do so
Only way to change the fan setting is to reprogram your chip. If it is coming on at 180, then it has been reprogrammed before or someone changed it before.
Only way to change the fan setting is to reprogram your chip. If it is coming on at 180, then it has been reprogrammed before or someone changed it before.
Le Mans Master
Joined: Feb 2006
Posts: 8,753
Likes: 9
From: Louisiana
I agree with the above. Your dash readout comes from (in 85) a coolant temp sender in the drivers side head betwen #1 and #3 spark plugs. In the later year L98 the sender is in the passenger side head between #6 and #8 spark plugs.
The main fan (between radiator and engine) is controled by the ECM which is given coolant temperature information from a coolant temperature sensor in the front of the intake manifold (resistance variable). You can either get a chip tuned to change the fan "on" temp or wire a switch in. On a scan tool you could notice a difference in temp readout on the guage and on the tool if one or the other (sensor/sender) is sending poor signal.
The t-stat controls the warm up time and minimal operating temp of the engine, only.
You also have should have a auxillary fan between the front bumper and radiator only seen from under the bumper. It is controled by a switch (in 85) in the passenger side head between #6 and #8 spark plugs. In later year L98 the aux fan switch is in the drivers side head betwen #1 and #3 spark plugs. The aux fan comes on around 235* stock. Your aux fan probably has spider webs on it.
The main fan (between radiator and engine) is controled by the ECM which is given coolant temperature information from a coolant temperature sensor in the front of the intake manifold (resistance variable). You can either get a chip tuned to change the fan "on" temp or wire a switch in. On a scan tool you could notice a difference in temp readout on the guage and on the tool if one or the other (sensor/sender) is sending poor signal.
The t-stat controls the warm up time and minimal operating temp of the engine, only.
You also have should have a auxillary fan between the front bumper and radiator only seen from under the bumper. It is controled by a switch (in 85) in the passenger side head between #6 and #8 spark plugs. In later year L98 the aux fan switch is in the drivers side head betwen #1 and #3 spark plugs. The aux fan comes on around 235* stock. Your aux fan probably has spider webs on it.
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
Originally Posted by Steeler1
Then I need a chip to change the temp that the fan comes on at?
RACE ON!!!
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Burning Brakes
Joined: May 2006
Posts: 1,097
Likes: 2
From: Richfield Utah
I have been trying to rationalize some people hooking there main fan on relay to the aux. fan switch in the head. Even if they change the aux. fan switch to a lower temp. How does the air conditioning turn the fan on/off then??? Wish I had a vol. 2 FSM wiring manual... 
Last edited by Steel Breeze; Oct 29, 2006 at 01:00 PM.
Thread Starter
Instructor
Joined: Dec 2004
Posts: 130
Likes: 0
From: Carlisle Pa.
I don,t think the main fan was wired into the aux. fan switch.
What I found was the wire from the harness to the main fan relay has a 30 amp fuse installed between the harness and the switch.... but with no fuse and one end taped up.
I found a hypertech sticker on the air dam.. so i'm thinking there is some kinda chip and that's why the lower t stat.
Any way to determine what the chip is without taking it out?
Car runs good kick into it at about 65 and i'm doing 100 in a heart beat
What I found was the wire from the harness to the main fan relay has a 30 amp fuse installed between the harness and the switch.... but with no fuse and one end taped up.
I found a hypertech sticker on the air dam.. so i'm thinking there is some kinda chip and that's why the lower t stat.
Any way to determine what the chip is without taking it out?
Car runs good kick into it at about 65 and i'm doing 100 in a heart beat
Le Mans Master
Joined: Feb 2006
Posts: 8,753
Likes: 9
From: Louisiana
The only way to check the chip is to remove the ECM and remove the cover to get access to the chip. It should say Hypertech on it. There is no way to know what is programmed into it from visually looking.
Team Owner
Joined: Sep 2001
Posts: 62,155
Likes: 1,731
From: Athens AL
C7 of the Year - Unmodified Finalist 2021
C4 of Year Finalist (performance mods) 2019
No the chip must be removed from the computer and plugged into a chip reader and a laptop or PC to determine what its' settings are.
