Recommended on and off temperatures for electric fans
 

I have decided to go the dual electric fan route to help with running the A/C. My big concern is when to have the fans turn off and on. I have the Holley Sniper so I can program any combination I want to control the fans. One thing the Sniper has the ability to do is turn on fan #1 anytime the A/C compressor is on. I have a Mildon high flow 180 degree thermostat and the car normally runs 180 degrees, maybe a little more on a hot day, when I am driving at higher speeds. It was recommended on the Holley Sniper forum that with a 180 degree thermostat to have fan #1 come on at 185 and off at 180 and fan #2 on at 190 and off at 185. Then another recommended fan #1 on at 190 and off at 185 and fan #2 on at 195 and off at 190, these seem a little high. A guy that installs the Snipers on Pontiacs for a living recommended fan #1 on at 170 off at 160 and fan #2 on at 185 and off at 175. With this one fan #1 would be on while driving down the highway without the A/C even being on.

So I am wondering what the Pontiac guys have found to work with their cars and what you would recommend?

Thanks,
Dale

Doesn't that Sniper EFI Need like 160 degrees before it start learning ? Also keep an eye on that high flow thermostat. Had bad luck with those sticking. I would try keeping temp around 180.

Yes, the Sniper needs 160 degrees to enter the learning mode. On the highway the temperature runs around 180 to 185. That is why I was considering running the #1 fan at 185 on and 180 off then fan #2 190 on and 185 off. If the thermostat is stuck it is stuck open, which could be causing some of the problems of the temperatures constantly creeping up.

Thanks for the information,
Dale

I also have a 180 high flow thermostat: https://www.summitracing.com/parts/emp-301

My dual fans are set as:

Low fan: on@190 off@185
High fan: on@195 off@187

How does that work for you and what are your temperatures at idle and cruise?


Dale

I'm usually at about 190 which I like for an optimal combustion. At idle I'm steady, but I attribute that more to my EWP. At cruise in 6th gear, my temp will creep down to 170 or even 165 on the highway. Even when it's 115 outside and I'm in stop and go traffic with the AC on, it never gets above 195-200.

My fender air extractors are functional tho and I have the proper lower air baffle installed, factory filler panels on the rad support, weather stripping between my rad and support, and the factory air diversion flaps for the side of the radiator. I'm running a 12 core C&R radiator as well so YMMV.

Sounds like a nice setup. I do well at cruise, usually 180 with the air on, sometimes 185. My problem is at idle, it continually creeps up until it is way too hot. I have tried a lot of things which has helped but it will still hit 220 and climbing, slowly, (before the changes it would peg the gauge at 245) but still climbing. If it got to 220 and stabilized there I would not worry about it. Plus, this gives me a chance to do another project I've been wanting to do. :)
Dale

Mine crept too until I did the EWP. I tried a FlowKooler and had my plate spaced perfectly. Once I added the EWP, it never ever crept up again. I use a PWM controller for my fans and EWP. Best cooling upgrade I did.

Never thought of an electric pump. I will keep that in mind if the dual fans don't work. I have a feeling they will because all of my temperatures are fine except for idle. All I have to do is set a fan in front of the car and the temperatures start to fall from the 220 point, which make me think I don't have enough air flowing through the radiator.

Dale

Try some more timing at idle.

Already tried that, didn't do any good. The only thing that helps is a fan sitting in front of the car blowing in the radiator. It doesn't have to be much, but it starts dropping the temperature instantly. That is why I have decided I am just not moving enough air at idle.
Dale

Dale. Get rid of that thermostat and put a stainless steel Napa Premium unit in.

Charles

Do you know what the part number is and is it a NAPA part?
Dale

Dale. This is our part # here in Canada. Yes from Napa THM PM1800025
PRODUCT LINE :
NAPA Thermostats
IMPORTANT INFO :
Temperature 180 deg.

I’ve also been told never to push on the bellows on the stat as it damages it.
Also, you can always check operation in hot water with a thermometer-before installing.

Thanks, I will check into that. I can always pull it out and check to make sure it is working properly if the fans don't work. But I have a feeling it is working fine because running down the highway with the air on with a temperature of 95 degrees outside the car runs at 180 to 185 degrees. Which to me says the 180 degree thermostat is working as advertised.

Dale

AC DELCO does make a 170 t stat.
Thermostat ratings are "Static"
MOST working cooling systems will run 10 degrees above the static rating.
This is your t stat / systems "Dynamic " rating.