[crv383]

What temp range do you see? Efans run any time the a/c compressor is engaged......the run constantly in "AUTO" mode.

I've observed well north of 200F coolant temp, efans off, not moving, 40F ambient. Kick the efans on and coolant temp drops rapidly, like a rock, floating 177F - 183F.

 

[crv383]

I just sent my ob2 scanguage in to have a software update and it won't be back till next week. I had the same drop as you (200+ to 175) by putting the car heater on full blast. I didn't know then that the defroster would also turn on both radiator fans too. Did not want to use the air conditioner on a hot day going up a hill just to turn the fans on. Just found out a couple days ago about the defroster. Plus you have the heater fan on, also pulling heat away from the engine...
I will experiment more next week when I get my scanguage back.

You will most likely see lower/steadier coolant temps in hot weather with the efans running constantly (a/c on). I also use a ScanGauge II to monitor coolant temp exiting the motor, coolant temp exiting the cold radiator tank and tranny fluid temp.

Defrost/defog are one in the same, with regard to vent selection, where the HVAC air blows from. If it's cold enough (ambient temp) to have frost form on the outside of the windshield (defrost), the compressor is probably not engaged (efans off). Defog clears condensation from the inside of the windshield by engaging the compressor to provide dehumidified air.

Please monitor tranny fluid temp before and after installing the cooler and post back with the info.