Temperature Switch
Burning Brakes
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Thread Starter
Instructor
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From: Miramar Florida
At what temp should this fan come on? There are conflicting ideas about which fan is primary. Some say the smaller fan that pushes air toward the radiator is the primary, others say that the big fan that pulls air through the radiator is primary, which is correct? I would think the primary would cycle on first and the secondary would come on at a higher temp if needed.
Burning Brakes
Joined: Nov 2011
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At what temp should this fan come on? There are conflicting ideas about which fan is primary. Some say the smaller fan that pushes air toward the radiator is the primary, others say that the big fan that pulls air through the radiator is primary, which is correct? I would think the primary would cycle on first and the secondary would come on at a higher temp if needed.
Last edited by caddyboy84; Apr 8, 2012 at 08:14 PM.
Le Mans Master
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From: WV
At what temp should this fan come on? There are conflicting ideas about which fan is primary. Some say the smaller fan that pushes air toward the radiator is the primary, others say that the big fan that pulls air through the radiator is primary, which is correct? I would think the primary would cycle on first and the secondary would come on at a higher temp if needed.
..Some C4s like mine don't even have a secondary fan.....WW
Last edited by WW7; Apr 9, 2012 at 07:19 AM.
Burning Brakes
Joined: Nov 2011
Posts: 841
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At what temp should this fan come on? There are conflicting ideas about which fan is primary. Some say the smaller fan that pushes air toward the radiator is the primary, others say that the big fan that pulls air through the radiator is primary, which is correct? I would think the primary would cycle on first and the secondary would come on at a higher temp if needed.
The primary is the larger fan that comes on first at 228..The smaller fan in front of the radiator is the secondary that comes on at 238.....(Primary- First)....(Secondary- Second).......WW
The primary is the larger fan that comes on first at 228..The smaller fan in front of the radiator is the secondary that comes on at 238.....(Primary- First)....(Secondary- Second)....
...WW
My small fan comes on first and my large fan NEVER comes on because my car never gets that hot, I guess I'm wrong. Wouldn't be the first time.
Last edited by caddyboy84; Apr 8, 2012 at 08:31 PM.
Le Mans Master
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From: WV
Last edited by WW7; Apr 8, 2012 at 08:55 PM.
Burning Brakes
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Below is a second opinion incase you don't believe it...If your small fan is coming on first, someone wired it to do that because the large fan is suppose to come on first , the small fan is suppose to come on as a backup incase the primary is having problems keeping the engine cool. On most early C4s the small fan was an option that had to be ordered..WW
. Would I be correct in saying that?
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Le Mans Master
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From: WV
So based on this information, our cars should be running at about 230 degrees? I'll be the first to admit I'm wrong, but based on all I've been told and how I set my car up, it appeared to me to be the way it was. I haven't heard of anyone having thier car run those temps. So I'll revise my answer to "I suggest doing it this way". Would I be correct in saying that?
. Would I be correct in saying that?Last edited by WW7; Apr 8, 2012 at 09:31 PM.
Burning Brakes
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Our cars aren't suppose to run at a constant 228 or 238 degrees, but in a situation like heavy traffic the can get this high. The secondary fan is a backup incase the primary can't hold the temperture low enough (228). The temps that these cars run is all over the place because of different levels of maintainecne through the years and different mods done to them. My 89 with a 383 engine never gets over 196 degrees even in stop and go traffic because of the mods I have done, which include a Dewitte's radiator , a high speed fan , and resetting my fans to come on at 195 degrees and off at 184..Most stock early C4s usually run around 190 -215 depending on the level of maintainence they have had and the region they are being used in...WW
I really need you to set me straight here on something, I've been told that the temp switch on the rear pass side head controls the large fan (Primary, I now know) and is controlled by the ECM. Heres the question; Is that true or is that just a basic temp switch that I can change to trip the large fan on at whatever that switches temp is that I choose?
Thread Starter
Instructor
Joined: May 2011
Posts: 213
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From: Miramar Florida
Below is a second opinion incase you don't believe it...If your small fan is coming on first, someone wired it to do that because the large fan is suppose to come on first , the small fan is suppose to come on as a backup incase the primary is having problems keeping the engine cool. On most early C4s the small fan was an option that had to be ordered..WW
Team Owner
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From: Cincinnati, Oh USA
The primary fan comes on at 228 F and the secondary fan comes on at 238 F. GM says to turn off the engine if the coolant temp reaches 260 F and let the engine cool down . They say this because 50% antifreeze at 15 psi boils at 265 F and the heads have the highest temp and boiling coolant cannot transfer much heat and the heads/valves could be harmed by excessive temp. If no boiling occurred, even 265 F will not harm an engine.
The primary fan on temp is controlled by software in the ECM from the temp sensor at the front of the engine under the MAF. The secondary fan on temp is controlled by a thermostatic switch in the block between cylinders #1 and 3.
When sitting in traffic that provides no air through the radiator, you should experience the main fan come on at 228 F and off at 211 F and then it will repeat. Underway, the coolant should settle at 195 F at the coolant temp sensor in the front of the engine with the factory thermostat.
The primary fan on temp is controlled by software in the ECM from the temp sensor at the front of the engine under the MAF. The secondary fan on temp is controlled by a thermostatic switch in the block between cylinders #1 and 3.
When sitting in traffic that provides no air through the radiator, you should experience the main fan come on at 228 F and off at 211 F and then it will repeat. Underway, the coolant should settle at 195 F at the coolant temp sensor in the front of the engine with the factory thermostat.
Le Mans Master
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From: WV
I understand I really need you to set me straight here on something, I've been told that the temp switch on the rear pass side head controls the large fan (Primary, I now know) and is controlled by the ECM. Heres the question; Is that true or is that just a basic temp switch that I can change to trip the large fan on at whatever that switches temp is that I choose?
I really need you to set me straight here on something, I've been told that the temp switch on the rear pass side head controls the large fan (Primary, I now know) and is controlled by the ECM. Heres the question; Is that true or is that just a basic temp switch that I can change to trip the large fan on at whatever that switches temp is that I choose?There are two or three temperature sensors (if you have the auxiliary fan).
The temperature sensor in the passenger side head between plugs #6 and #8 is the sender for the temperature display in the instrument cluster.
The one on the front of the intake manifold goes to the ECM. The ECM determines when to turn on the main fan.
If you have an auxiliary fan in front of the radiator, it is controlled by a temperature switch in the driver's side head between plugs #1 and #3. You can change the auxiliary fan turn on temperature by buying the appropriate temperature switch.
The temperature sensor in the passenger side head between plugs #6 and #8 is the sender for the temperature display in the instrument cluster.
The one on the front of the intake manifold goes to the ECM. The ECM determines when to turn on the main fan.
If you have an auxiliary fan in front of the radiator, it is controlled by a temperature switch in the driver's side head between plugs #1 and #3. You can change the auxiliary fan turn on temperature by buying the appropriate temperature switch.
... Below is a kit to lower your temps if thats what you want to do...You can also change the fan on and off temps in the chip...WWhttp://www.ecklerscorvette.com/corve...1984-1995.html
Last edited by WW7; Apr 8, 2012 at 09:57 PM.
Burning Brakes
Joined: Nov 2011
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The primary fan comes on at 228 F and the secondary fan comes on at 238 F. GM says to turn off the engine if the coolant temp reaches 260 F and let the engine cool down . They say this because 50% antifreeze at 15 psi boils at 265 F and the heads have the highest temp and boiling coolant cannot transfer much heat and the heads/valves could be harmed by excessive temp. If no boiling occurred, even 265 F will not harm an engine.
The primary fan on temp is controlled by software in the ECM from the temp sensor at the front of the engine under the MAF. The secondary fan on temp is controlled by a thermostatic switch in the block between cylinders #1 and 3.
When sitting in traffic that provides no air through the radiator, you should experience the main fan come on at 228 F and off at 211 F and then it will repeat. Underway, the coolant should settle at 195 F at the coolant temp sensor in the front of the engine with the factory thermostat.
The primary fan on temp is controlled by software in the ECM from the temp sensor at the front of the engine under the MAF. The secondary fan on temp is controlled by a thermostatic switch in the block between cylinders #1 and 3.
When sitting in traffic that provides no air through the radiator, you should experience the main fan come on at 228 F and off at 211 F and then it will repeat. Underway, the coolant should settle at 195 F at the coolant temp sensor in the front of the engine with the factory thermostat.
Le Mans Master
Joined: Aug 2007
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From: WV
I did not tamper with the operation of the main fan and it comes on around 228 or so(I made my car get that hot to check the system properly) or when I put on the A/C. So is it true that the primary fan "temp-on-point" cannot be changed without making an ECM modification with a chip? And, what is that temp switch on the rear passenger head for? This is very important to me because I've been handed and passed on alot of misinformation, which I'd never want to do. Although how I have my car set-up seems to be a good working combination and serves it's purpose well, it's not factory parameters.
.....WW
Burning Brakes
Joined: Nov 2011
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I have a couple of calls to make and some screaming to do. I guess there really is three sides to a story, BS more BS and the truth. There is someone else with a similar thread right now that needs your help, uhhh....I kinda misinformed them
.
Le Mans Master
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From: WV
Thanks for clearing that up. I thought the smaller fan should have been secondary. The 228 temp seems high even though everyone I talked with say it normal for the engine to get this hot. Mines usually runs around 220-228 depending on weather. I'd like to see it lower, what can I do? I changed the thermostat to a 160* today, what else will help?
..WW
Last edited by WW7; Apr 8, 2012 at 10:28 PM.