With a stock motor having a 195 t-stat in it, the stat would open before the fan comes on with a stock fan switch at 237. with a cooler switch that comes on at 200, supposed to shut off at 185, it just isn't shutting off, even tho the engine has cooled down. since the t-stat and fan kick in about the same time, the fan cools it off quick, so the t-stat closes back up, but like i already said, the fan stays on...

with all that said, seems to me under "stock" conditions that the fan would never come on unless it was getting really hot, adding to my point that the fans are not designed to stay running constantly for the most part, only if a really hot condition exists, or with extra load, such as A/C.

i've changed the fan switch out, but it still does the same thing, even though the fan pulls it down to about 170, just stays running. so, what would be the effect of putting a 180 t-stat in there instead? is the t-stat supposed to be open under normal conditions? it just seems to me that it should open and circulate coolant long before the fan has to come on...

 

Your observations and theories seems correct to me so I'm at a loss to understand what's going on.. The only thing I can point to is that the stat and the cooler switch measures the temps in different places, whatever effect that may have. Maybe the cooler switch actually has a broader "hysteresis" than specified?

 

yea, it could have a broader "hysteresis", but again, i'm not thinking the fan system was designed to run the fans most of the time, only to cool as needed like sitting in traffic, etc. 237 is pretty hot, stat woulda' opened long before (hopefully).

Anyways, i guess i need to know if the stat is supposed to be open under normal conditions, once the engine reaches temp. if it is, then i need to either lower the stat temp to 180, or raise the temp on the fan switch to prevent it from running all the time. by the way, i know when the fans are in operation by having indicator lights on the dash...

 

The thermostat will be open as long as the coolant temperature is above the opening temperature.

 

In my world of thinking the stat should open some 10-15 degrees before the fan kicks in..
You are right in thinking that the fans should run only when not moving or with A/C on.
The stat has a temperature range of some degrees from barely open to fully open, but no hysteresis. It should pe partly open under normal driving conditions. The 180 stat would stay more open under the same conditions and so might actually aggravate your problem.. But the only way to find out for sure is to try..