Grille block effect and ICE temp specs

Now that I have a scangauge I'm curious to see what the actual effect of my grille block is (which I haven't put in yet this year).

On my last long drive a couple of nights ago (mostly non-interstate, speeds 50 - 60 mph except going through towns and a few interstate stretches, temps 30 to 40 F), without the grille block, I noticed the ICE temp stayed right around 83 C the whole time, which is just 1 C above where the thermostat first cracks open. So it looked like in those conditions, the thermostat is able to limit cooling enough to maintain the ICE temperature.

What effect should I be looking for as the weather cools and I add the grille block? Will there be outside conditions where the ICE doesn't reach thermostat opening temp without the block, but does with the block? Or is the expected effect just to reach that temp faster?

And btw, what's the comfortable ICE temp range considered to be? I notice on page CO-11 that the thermostat is supposed to crack open at 82 C and be fully open by 93 C. I tried to look up the set points for the cooling fans and got confused by what might be typos in the manual.

There's a table on page CO-20 that says the fans should be running at low speed for 88 C "or below" and at high speed for 98 C "or below".

That would make more sense to me if the belows were aboves.

There's a nearly identical table on page AC-67 except it changes one below to an above - that one says low speed for 88 C or below, high speed 98 C or above. Which still doesn't seem right. And also, both of these tables are for test conditions including AC turned on.

Ok ... in the wiring diagram the fans start (low speed) when relay 3 closes, completely controlled by the water temp switch W4 (which also asserts the CF signal to the A/C controller, unless that's an output, in which case the A/C controller can also start the fans). Things bump to high speed when relays 1 and 2 switch, which happens when the A/C pressure switch A3 closes (also asserting the "FAN" signal to the ECU and the "RF" signal to the A/C controller).

So it seems like the temperature I'd like to keep things below is whatever the ON temp is for the W4 switch. (No need to block cooling so effectively the fan has to run.) But so far I haven't found a test for that switch that states the temperature. There's an Engine Coolant Temperature Switch test on page AC-84 but that seems to be a different animal (you remove the inverter to get to it, where W4 appears to be down on the corner of the radiator).

So on page DI-867 it kind of looks like CF on the A/C controller is an output (run the fans on low whenever A/C is on?). Also FAN on the ECU might be an output (else how could RF at the A/C controller be driven low by 90 C water temp, as also suggested on DI-945?). Either that or these diagnostic tables are also in error and the 90 C water temp should really be listed next to CF, and would be the switch temp of the W4 water temp switch (which is what I'm looking for).

Phooey, I expected this to be easy to look up. Does somebody know the operation of the fans better? Will I have to just go try to get the water hot enough for the fans to start and note the temp? (That might not be easy in November.)

Thanks,
-Chap

 

CF from the A/C board is definitely an output; I watched the fans start on low unconditionally whenever the A/C is engaged.

I still haven't found the temperature at which water temp switch W4 starts the fans on low for ICE temp alone. I was able to reach 89 C doing a force charge in the driveway but that wasn't enough.

-Chap