Fan Control

[Gorgon]

I've read through some other posts on overheating and fan control and have a couple questions. My 95 gets warm and I manually have to turn the A/C on to get the fans to come on to cool the car down. What is the stock temp for the fans to come on at? And does the ECM enable the same switch that turning the A/C on would? Is there a separate relay somewhere I should be looking for?

Leon

 

[WhalePirot]

Congrats on searching before asking. My search of 'cooling fan' yielded:
http://www.corvetteactioncenter.com/forums/showthread.php?t=57874&highlight=cooling+fan

Stock fans typically start at 230, shut off at 210; hotter than most of us prefer.

Yes, there is one fan relay, activated by whatever source. Later '85s and up, used the ECM to kick on the fans. The A/C switch also activates it.

While other solutions exist for triggering the fan, it may not be a bad thing to use the A/C switch, as one should run it weekly or so, to keep the seals and all in shape. If your car is not cooling properly when moving, perhaps you have debris blocking airflow through the radiator or another cooling issue.

 

[Hib Halverson]

With the hvac off the fan-ons are as listed above, however, with the hvac on, the fans are commanded on all the time below a certain vehicle speed...40mph, I believe. This is why turning the hvac on, usually makes an immediate difference in cooling. With a 95 LT1, I believe you can use the HyperTech Power Programmer to lower the fan-ons.

 

[Gorgon]

Thanks guys. I saw that thread in my search but didn't get the 230 temp. I believe I'm running hotter than 230 and the fans dont' come on unless I kick the HVAC on. If the fans come on with HVAC but not by the ECM at the normal temp of 230, where should I be looking to correct this? The goal is to eventually set the turn-on temp lower with some programming, but I think in its current state that would be irrelevent if it's not turning on corretly to begin with.

Leon

 

[RonJ]

I believe you can buy temperature sending units that will make your fans come on earlier. Check out Ecklers or any of the 'vette catalogues.

Ron ...

 

[Tim Scales]

You can purchase from Ecklers or MA Motorworks a simple fan on and off switch to turn on your cooling fans(s) at will. I have this on my '92. However one word of caution, DO NOT leave the SWITCH ON and RUN the AC or defroster at the SAME time or you will set a code...in mine a code 28.
The switch turned on will lower the LT1 temp 30 degrees if I slip up and let it get HOT in stop and go traffic. Summer I run 160 Therm. Winter the stock 180. A great buy too at less than $20.00 comes with all wiring and switch needed with instructions. Check with them to see if your model is available. Good Luck...Tim

I've read through some other posts on overheating and fan control and have a couple questions. My 95 gets warm and I manually have to turn the A/C on to get the fans to come on to cool the car down. What is the stock temp for the fans to come on at? And does the ECM enable the same switch that turning the A/C on would? Is there a separate relay somewhere I should be looking for?

Leon

 

[Gorgon]

The problem I have with a manual switch is I want it to be automatic. Why should I be worrying about temps when I should be DRIVING the car.

Doing a little test tonight, both fans come on around 228 and shut off at the same time around 216. Too warm for me. Now if the A/C is turned on both fans come on but they are much louder, like one (or both) fans are in a high speed mode. Why wouldn't they blow this much air normally? Looks like a 180 stat and a program is in order, or one of the relays spoke of here.

Leon

 

[WhalePirot]

The problem I have with a manual switch is I want it to be automatic.

Here, here.

, both fans come on around 228 and shut off at the same time around 216.

The temperature sending units will vary some. I'd shop for one that triggers at a lower figure.

I run a RobertShaw 180 with fine results. AutoZone: $7. I chose the 'Shaw' as it flows more coolant than the Stant, which made a big difference in my engine; more than the aftermarket radiator and more than the high-flow pump.

Lots written elsewhere, as you probably saw, about 180 vs 160. Remember, it is a water SWITCH that starts to open at the rated temperature and cycles open and closed. Thus, it keeps coolant in the block long enough to cool it and in the radiator long enough to cool the coolant.

 

[Hib Halverson]

Thanks guys. I saw that thread in my search but didn't get the 230 temp. I believe I'm running hotter than 230 and the fans dont' come on unless I kick the HVAC on. If the fans come on with HVAC but not by the ECM at the normal temp of 230, where should I be looking to correct this? The goal is to eventually set the turn-on temp lower with some programming, but I think in its current state that would be irrelevent if it's not turning on corretly to begin with.

Leon

You need to *know* your running hotter than 230.

Do you see 230 on the digital display?

 

[warren s]

I know you didnt want a manual switch, but if you are wondering how simple it is to install -

http://community.webshots.com/album/102276848UPNpsc

 

[Hib Halverson]

The problem I have with a manual switch is I want it to be automatic. Why should I be worrying about temps when I should be DRIVING the car.

Doing a little test tonight, both fans come on around 228 and shut off at the same time around 216. Too warm for me. Now if the A/C is turned on both fans come on but they are much louder, like one (or both) fans are in a high speed mode. Why wouldn't they blow this much air normally? Looks like a 180 stat and a program is in order, or one of the relays spoke of here.

Leon

As this car is a 95, let me clear-up some misconceptions. First, 95s have no "senders" which control fan ons. The fan-ons are commanded by the engine computer. If you want fan-on temp to be lower and you want it to work automaticly (by far the best way---those using manual switches are just fooling themselves---yes the engine runs cooler at times, but the temperature control is inconsistent), the only way is to change the ECM calibration.

You can have someone reprogram your ECM or you can do it yourself with a device such as the Hyper Tech Power Programmer or software such as LT1 Edit.

Keep in mind that just lowering the fan-ons may not be all you need to do. If the cooling system is not maintained properly, it may not be able to sustain a lower temperature in traffic and, on really hot days, even if it's in perfect shape, it won't be able to sustain a significantly lower temp.

 

[warren s]

As this car is a 95, let me clear-up some misconceptions. First, 95s have no "senders" which control fan ons. The fan-ons are commanded by the engine computer. If you want fan-on temp to be lower and you want it to work automaticly (by far the best way---those using manual switches are just fooling themselves---yes the engine runs cooler at times, but the temperature control is inconsistent), the only way is to change the ECM calibration.

You can have someone reprogram your ECM or you can do it yourself with a device such as the Hyper Tech Power Programmer or software such as LT1 Edit.

Keep in mind that just lowering the fan-ons may not be all you need to do. If the cooling system is not maintained properly, it may not be able to sustain a lower temperature in traffic and, on really hot days, even if it's in perfect shape, it won't be able to sustain a significantly lower temp.

Hib-

I respectfully disagree with much in that last post of yours. After changing my thermostat and installing the fan switch I was able to maintain the coolant temp. in my car below 200 on the hottest of days in all types of traffic and for any length of time. In my area that would be the high 90s. I did put some mileage on the car and never seemed to miss the "Cool degrees" staring at me.

I don’t consider monitoring the digital readout and driving to be something akin to juggling chainsaws. I would of course prefer to have it work automatically, but for a total investment of less than $25 to keep my C4 from ever reaching 235 degrees, I think it was a good deal and I wasn’t fooling myself or any one else I did the fan switch install for.

 

[WhalePirot]

My guess, Warren, is that the 160* stat had a little to do with the cooler running and that the fan's running had everything to do with it. That is, unless, there were coolant flow issues before.

Such was my experience, after running too hot with a 'SUPER' radiator and pump. Low speed airflow is a problem, but as my fan kicks on automatically, coolant temperature issues are gone.

Now, how do I reduce the underhood temperature when moving slowly? <<Partially explored in an old thread.

 

[warren s]

Actually the 160 had much to do with it on my 95, other year C4s may be differnt.

The car came with a 195 t-stat stock. When i ran the fans with the stock t-stat the coolent temp wouldnt go below an indicated 190. Even on a cooler day. i did try that first. After the change to the 160, with both fans running the coolant temp would go to between 100 to 110 degrees above the ouside air temp.

I did remove and clean the radiator before all of this. Funny how you mention underhood temp, thats what started my obsession with the fans switch, when i purchased the car all of the underhood vac lines and hoses were baked and brittle, and the car had only 13,800 miles on it. After I replaced them and got the motor to run cooler everything seemed affected. I could even rest my hand on the throttle body after a long ride. Not so when the temp was reaching 235.

 

[Tim Scales]

Warren...
I could NOT have said it any SIMPLER or any BETTER my friend....Tim

 

[ltmark]

Here was my solution on my '85. I have both fans. The ECM kicked in the primary fan at 228 and the AUX fan came on shortly thereafter. So.......I

1. put in a 195 degree temp switch in the AUX head port near #8. I then ran that wire to the Primary fan relay.
2. Moved the ground wire from the ECM in the primary fan relay to the Secondary fan relay.

Now, the primary fan comes on at 195 and the AUX at 228. One reason I like this is the primary fan is a lot more efficient and the secondary is a lot louder!

Total cost (1) 195 degree thermo switch 5 bucks, or so!

 

[vette fever]

Thought I was too HOT!!

Thanks for the info. I was ready to take my 2002 to the shop before reading this. We got home from a trip and it was at 228 which I thought was too hot. I joined Corvette Action Center after reading to clean out the radiator housing. We had alot of leaves and pine needles up there. I took it for a ride tonight and it was 212 when I got home and no fans running and really thought something was wrong. I am going to try the A/C and make sure they come on. I too am interested in running cooler. Thanks again guys! John
Running hot--need advise quick - Corvette Action Center

Stock fans typically start at 230, shut off at 210; hotter than most of us prefer.

Yes, there is one fan relay, activated by whatever source. Later '85s and up, used the ECM to kick on the fans. The A/C switch also activates it.

While other solutions exist for triggering the fan, it may not be a bad thing to use the A/C switch, as one should run it weekly or so, to keep the seals and all in shape. If your car is not cooling properly when moving, perhaps you have debris blocking airflow through the radiator or another cooling issue.[/QUOTE]