Does anyone know if the O.E. electric fan in front of the radiator has a default setting built in to activate if the coolant temperatures reach higher than considered acceptable by the ECU? It seems to make sense to utilize it since it's already there and it could help out in an emergency situation. If not, maybe it could be wired to a switch? Just wondering.

Simple answer: Yes.

Complicated answer: 90-93 have thermostatic switch in the radiator that activates the fan at 210 degrees as well as the independent circuit from the AC cluitch control.

94-96 USA models have two-stage fan controlled by ECU considering temp. 94-96 Canada models have single-stage fan controlled by ECU. 94-96 do not have thermo switch, but do have independent AC clutch circuit control.

so its true that my fan on my 94 wont work with the 9093 ECU? I dont think it will overheat, but it shoudl come on as normal with the AC , yes?

That's great to know since I have removed my belt driven fan now. I've driven around for a couple of days (mid 30's temps) and the temperature gauge stays right in the middle (normal for mine) while driving and idling (must mean the fan clutch doesn't have to engage very often). Nice to know that it'll kick in if things heat up too much although I'm not relying on it to cool the whole engine under all conditions. It'll due till I get the main electric fan installed. I also like the engine response without the mech. fan. Seems more resposive and the revs climb quicker.

did you get your springs yet??

Not yet, from what I understand Simon put the wrong address on them and FedEx is tracking them down.

Ok... sounds good..... sorry for the delay.

Wes: Yes, that's true. It probably won't be an issue for 99% of people - my fan never comes on unless I run the AC.

[QUOTE=Flagship-Q]That's great to know since I have removed my belt driven fan now. I've driven around for a couple of days (mid 30's temps) and the temperature gauge stays right in the middle (normal for mine) while driving and idling (must mean the fan clutch doesn't have to engage very often). I tried running engine on 91 G50 before without fan clutch assembly and Aux. Fan kept coming on every minute or so back to back to back! I checked Temp. gauge and readings never exceeded the normal operating Temps. but, I never heard fan come on before until then! I soon changed back because too much heat is bad for Aluminum Heads and Eng. life!

When members post a number please check the FSM first.

The [90-93] auxillary fan is first activated at 189-199F by the thermoswitch...[not 210F as postulated]....the mean is 194F just like the point where ignition advance starts being removed from ECU equation.

174F is IDEAL and 194F+ is the beginning of the over heat range where the theromstat in coolant system loses control [100% open]........duh why the auxillary fan comes on.

Being lose with THE NUMBERS is how we see overheats and engine destruction. 15F lower is a big number. Turn AC off in Summer, if fan still runs for more than a few minutes [5 minutes] you have rad problems!

Doesn't matter WHAT the FSM says, the electric fan turns on at 210 degrees according to my thermometer!

ECU does not start removing timing advance until 200F, not 194 (according to ECU code).

Well mine [Dinan reprogram] reduces the advance 1 degree at 195F as reported by the Consult. I graphed mine and many other car coolant temp [as reported to ecu] vs advance.

Have you removed the thermoswitch and checked it in water? Insulative corrosion on switch builds up and they become progressively less senstive.Have you checked 3-4 and measured the variances? We use a very accurate IR gun to double check them. [not a $99 special but a reference $795 version accurate to 1F].

One day I checked 6 brand new ecu coolant thermistor for resistance immersed in the same hot water the variances were +- 3F as read by ecu bridge - still well with manufacturers spec.

But then again what is 5F in the scheme of things with the typical used radiators in service.I have a thicker [extra quart] custom all Aluminium monster made by Griffin.
Why I trimmed mine [my ecu coolant temp sensor] to be accurate at 194.0F [series parallel resistors].

REMEMBER the fan sensor is on the output side of the the radiator and the coolant sensor is on head output before theromstat...........there should be 5-7F difference in coolant temp between the two.

Doesn't matter WHAT the FSM says ????Not sure you really meant to say this, as there a few mistakes in the document.