Scottie-GNZ Posted April 6, 2007 Share Posted April 6, 2007 I searched but could not find exactly what i am looking for. Hopefully I can get answers from people in the know and not just guessing. No offense to anyone. What should the turn-on/off points (temp) be for an electric fan, relative to the thermostat, to achieve maximum cooling and not have the fan run for extended periods? IOW, when should the fan turn on relative to the thermostat opening? For sake of discussion, it is a 180*F thermostat. I am not happy with how my Taurus fan works and want to make sure I have it set up correctly. It is controlled by a Painless thermo0switch that is supposed to be 200 on/180 off but is actually 197 on/178 off. Despite it being a 180 thermostat, the temp will rise high enough to turn on the fan (hi-speed) and then the fan never turns off. On occasion the temp will even rise to 200 and stay there. It is not even the hot season in FL yet. Quote Link to comment Share on other sites More sharing options...
VinhZXT Posted April 6, 2007 Share Posted April 6, 2007 Hi Scott, How are you doing? I have EFI Live software and I've been messing with the temperature settings for the electric water pump and the fan. The stock LS1 fan setting is 190 on and 180 off. The t-stat is 180 degree btw. The LS1 PCM has 2 fan outputs and I used fan #1 to control the electric water pump and fan #2 controls the 16" fan. The 16" fan is at the stock setting 190 on and 180 off. For the electric water pump I initially had it set at 170 on and 160 off. I noticed when the electric water pump turns on it kept the water temp around 160 to 170 so the fan was never on. I remove the fuse for the electric water pump to see when the fan turns on and it sure did turned on at 190. As soon as the fan turns on I put the fuse for the water pump back and the tempt goes back down to around 160-170 and the fan stops. Now I had the water pump sets at 180 on and 170 off and it works great. Back to your situation I think your fan is turn on a bit late. It should be turn on at 190 and off at 180. Also I have 2 LS1 Zs and both have Griffin radiators. The one with the thick radiator cools down a lot faster then the other. I hope I am not wasting your time with my info. Vinh Quote Link to comment Share on other sites More sharing options...
COZY Z COLE Posted April 6, 2007 Share Posted April 6, 2007 I'm not sure this is the info you want so just ignore it if it's not. With my set-up ( a heat generating blower/355 SBC) I have the Taurus 2-speed fan also with a 180 thermostat. Low speed comes on at 185 degs. and high speed at 210 degs. Even in 60-70 deg. weather my temps rise to 190 degs. therfore kicking on the low speed fan. 200 degs. at a stop light is normal for me but still with only the low speed fan on. For me to go over 210 degs. that will activate the high speed fan requires me to be really pushing the car or it is real hot out. My car runs at low speed on alot but that's the nature of a blower motor. I've had this set-up 4 years now and the motor is still kicking butt. LARRY Quote Link to comment Share on other sites More sharing options...
SHADY280 Posted April 6, 2007 Share Posted April 6, 2007 its kinda funny actually, i was starting to think the same stuff here the other day. i run a 195 in my s130. the guys at a rad shop said that a lower heat opening thermostat, will actually hinder cooling, by letting the collant cycle too fast, thus the rad cant cool it. i had a 180 (trying to get it to cool down) if you have a thicker, denser, high performance rad, it will flow too much and cause a overheating problem. i run a very cheap fan that runs always as long as the key is "on" it seems to work, but the fan doesnt flow lots so my temp creeps past the center all the time, but never goes higher. just a little food for thought Quote Link to comment Share on other sites More sharing options...
Bartman Posted April 6, 2007 Share Posted April 6, 2007 I think the real issue is how hot your engine is running. It sounds like your engine runs at over 178 degrees even when the fan is running therefore your fan is constantly on. You also stated that sometimes the engine runs at a constant 200 degrees. I don't know what the normal operating range is for the type of engine you have, but if the temperatures your experiencing are abnormally high, the source of the problem doesn't sound like it would be related to when your fan turns on and off. If the temperatures you are experiencing are normal, then it sounds like you should raise the turn off point for your fan so that it isn't constantly on. Just my 2 cents. Quote Link to comment Share on other sites More sharing options...
viperredls1z Posted April 7, 2007 Share Posted April 7, 2007 i run a very cheap fan that runs always as long as the key is "on" I have been wondering about this since I recently put a manual override switch on my fan. Is there a point at witch vehicle speed surpases fan speed and could "over rev" the fan and do damage? or is there always enough resistance to airflow through the radiator to keep this from hapening? Quote Link to comment Share on other sites More sharing options...
Scottie-GNZ Posted April 8, 2007 Author Share Posted April 8, 2007 If the temperatures you are experiencing are normal, then it sounds like you should raise the turn off point for your fan so that it isn't constantly on. Just my 2 cents. Yes, I believe the on/off differential of 20* is too much but it is a non-adjustable thermal switch so I will have to try something different. Quote Link to comment Share on other sites More sharing options...
SHADY280 Posted April 9, 2007 Share Posted April 9, 2007 i think the fan just goes faster when driving at speed, it just seems to freewheel. my fan has been on my daily car now for 3 years, and only had a problem when it had a temp switch. thats why i run it off a switched source now. along with my injector cooling fan, its on the same circuit switch. last thing you need is one more part to break and cause the motor to overheat in traffic. Quote Link to comment Share on other sites More sharing options...
Tony D Posted April 9, 2007 Share Posted April 9, 2007 What I did on my 73 was use an Electrically Controlled Hayden Fan Controller. I waited for a HOT day (109F), and then got the car out on the highway---obviously the fan should NOT be running at that point on level ground and cruising. I noted where the thermostat was keeping the car (160 degree Chevy T-Stat). I then took the car off a frontage road, and put the car in fifth gear, and sloooowly let the car slow down till I saw the temp rise...then sped up slightly. This happened to be right around the lug-point on my car---around 35 MPH in fifth. I set my fans to kick on about 10 degrees above that 'low lug point'---it ended up being around 180 (even though it was a 160 t-stat!). Apparently that is the slowest I can drive and not have the car continually spiral up in temperature. So the fan kicks on at 180-185, and will shut off at around 170-175. I can watch this in traffic, and going down the road. Running on the freeway, the engine stays much closer to 160-165, when I pull down onto surface streets, the car will run 165-175, until I hit a stoplight. I can watch the temperature rise, and then the fan kicks in. As the fan does it's business, I can watch the needle on the gauge go back down to the cutout point, and can hear the fan shut off. It really gives me piece of mind that it operates in two distinct ranges. If it's climbing on the road I suppose eventually the fan may come on, but it hasn't done so thusfar. And in the stop and go of downtown L.A. the on-off keeps me from overheating. To my choice of thermostat: I figured the cooler everything was under the hood, the better. I tried this same setup with a 190 t-stat, and the car would surge and buck from vapor lock or whatever. But with the 160 in there, everything is so much cooler to the touch (intake manifold, fuel lines, etc) and I don't get any of the surging I got when running the hotter setups. Basically, as long as I'm moving forward in clean air, I have never heard the fans come on, and the car stays cool within reason. But slow way down and stop, and the fan will cycle, just like an OEM setup. Carbbed Car, btw. hope that helps you with the setup. It has worked well for me since about 91 when I changed to the twin Hayden 10" fans, from the old 16" Japanese Refrigeration Condenser Fan I formerly had on there! Quote Link to comment Share on other sites More sharing options...
waynekarnes Posted December 30, 2007 Share Posted December 30, 2007 i use a 185 fan switch off the intake manifold ( chevy ) for the low speed. using Cozy's schematics/relay set up, i use a european only corvette 205 degree fan switch for the high speed. it is mounted on the top of the water pump. i read that this is the temps that corvette engineers set for their high speed to come on. if this is where engineers want it to be, who am i to 2nd guess em ? supposedly the 205 degree fan sw is european only because of the high speed driving they do there. a safety factor. i used the 205 fan sw instead of manual sw in Cozy's schematic as prefer thing be idiot proof. with the jtr radiator, high flow aluminum water pump, high flow thermostat, and taurus 2 spd fan on 100 degree day, in my driveway, engine idling for close to 30 mins, the high spd never kicked on, the low spd cycled on and off. temp ga was right at 185. as a test, i grounded the 205 fan sw, low spd shut off, high spd came on. i blocked the radiator off with cardboard, took about 4 mins for the high speed to come on. seconds after high came on, i pulled the cardboard, let air flow again. temps dropped, fan went silent. thought i broke something. temps below 185. all was fine. low spd cycled off and on again. chevrolet suggests, 185 and 205. if you worry about detonation, you may want to run 165 as low fan sw temp, this may allow you to run a hotter spark plug. Quote Link to comment Share on other sites More sharing options...
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