yeah, like I said, I will plug in the lap top and use it to monitor the efi temp sensor.
I will rewire my stock sensor to use with your board, and then build my self the solid state VR for the intrument cluster so you can drive that gauge.

Did some testing today with the stock temp gauge. Seems to work pretty well.

Andy, I have a couple extra VRs if you want one to gut and your put your own regulator in.

I can also send you this box so you can monitor the actual % the fan is running at.

box might be interesting.
just need 12 volt and a ground? just wondering if it would be easier with my laptop or the box.

I have a couple vr's in my tool box, so don't need that. thanks.

The box has the fan controller in it, in addition to the display and 5v supply for the gauge. So, all of the lines (fan control, temp sensor, AC) would need to be run there. Inside the box, the power and ground need to be doubled up to power the other stuff.

With the box when you're going down the highway you can see exactly what the fan is doing, which may be useful at this point.

I agree, from a testing stand point, that would be helpful.
if it is okay, I may make mods to the wiring for testing purposes,
like wire it to control my temp sensor instead of the one in the box.

yea, that would be fine. I may be able to use a smaller box if I don't have to fit the extra 5v power supply. Can use an even smaller box if I stick the controller's screw terminal just outside the box

I'll put another one or two together, and send the box to you early this coming week.

UPS says the box is out for delivery

just got it.
probably won't get to it till this weekend. but just letting you know.

That's fine. I have another board in the truck right now, and I've noticed I have a bug to squash, so I'll have to send you an updated file to program it with

Will the controller work for both fans ? Oem and the aftermarket ones.

I am using an oem and have tested with the earlier oem that the aftermarket are based on, but I don't think any of us have gotten an aftermarket.

well good news bad news.

I got the controler wired up and reading on my regular temp sensor.
bad news is, it doesn't read right at the point where it needs to turn on.

reads fine right up till 200 degrees and then suddenly pegs..

Will work with dave to see what is up, or switch to an alternate temp sensor if I can't get a stock one to work.

Yep, unfortunately, we may not be able to use the stock sensor as it has very small resistance change between 190* and 220* (only about 10 ohms). In contrast, the GM sensor has 240 ohms difference in that range.

This means if the stock sensor is off by even a little bit, it throws the temperature way off. I got three sensors from the junkyard to test. The two that were closest, were 10 ohms apart from each other. The third was 100 ohms off.

Right now we're looking at using an Autometer sensor that will thread in place of the stock sensor. The controller can still drive the stock gauge in the dash, so I think it will end up working just fine

ok, I got the temp box up and running. it controls the fan, but I dual wired my on off just incase.
Apparently it can control the fan with just the speed wire, which is weird.

Was like 101 today, and I went cruising around in the vert to try this out.

I think a bit more fine tuning of the program is in order, but it seems to take care of most of my concerns.

at 35 mph my car does not need the fan. maintains 200 degrees with no issues.

At idle, the controler kept the fan speed about 25 percent, as high as 50 percent depending on what kind of run I just had.

I decided to see if the fan impeded flow, but did not get to do any high way runs.
but took the car from 0 to 50 mph pretty quickly, while the fan was trying to hold about 37 percent.

About a mile down the road, the fan showed it had shut off due to low temp, so that is pretty good.

After an extended 50 mph run in city, I basically backed into my garage, and it caused the fan to spin up to start with at about 65 percent, all the way to 85 percent.
Temps got up to about 220, but never higher.
It might have hit 90, but I don't think so. due to the sample rate, I think it kept low enough not to spin up higher.

all in all, it works, as a basic fan controler, next I will have to play with a/c signals and extended freeway driving in our wonderfull summer weather in spring.

Are both types of controllers ready to sell?

still fine tuning some of the logic I think.
I am driving my car with the variable speed setup.

not sure if it is my sensor, how I have it bolted in, or what, but still checking it out.
in the middle of moving right now, and have not had as much time to try it out as I would like.
been running errands with the car when I can to see how it handles 100 degree weather.

so far it has erred on the side of caution, and no
"real" temps over my regular efi settings. but the gauge he sent is a bit off compared to my computer, and I am trying to figure out why.

I was finally able to put some miles on it today. Did about 90 miles, mostly highway, with about 10 on a gravel road.

I'm pretty sure I still have some sort of cooling issue, but it kept the temperature within +/- 4* of the target temperature.

I have a 180* thermostat installed, and a target temperature of 203*. Outside temperature was in the mid 60s.

On the highway, it would creep up to 203, then fan would turn on, and by 206ish the fan was at full speed. It would pretty quickly drop to 203, and the fan would be back to idle by 201*. Wait a few more miles for the temp to creep up and it would cycle again.

On the gravel road the fan was at idle most of the time, staying right under 203*.

I'm going to tweak the algorithm again tonight, as I need to drive the same loop again tomorrow.

I think I'm really close to having an algorithm that should work well on most all cars. The problem I'm discovering is that my truck has an incredibly slow feedback time between when the fan speeds up and the temperatures respond. Andy's car is apparently the opposite; the fan comes on and the temps drop. I think I've found a way to adapt to either case automagically