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not sure if this is possible but is there a way to adjust the aux fan to come on at a lower temperature. It’s set at 212, I think. Is the fan activated by a sensor on the fan or a signal from the ECU?
According to the ETM, the ECU is fed the signal from the temp sensor and then switches ground at a particular set point which energizes the fan relay to engage the fan, which does not appear to be adjustable. If you were to hack it with your own manual switch you could do this between the fan and its relay or by supplying ground to the relay however I'm not sure if the ECU would care if you backfed ground to it.
If your fan is coming on, you probably should check your engine temp with an ODBII dongle and a phone app (I use Garmin Mechanic on mine). If you haven't changed to a grey 180 degree thermostat, I would do that first.
The engine temp sensor on my 02 Westminster project is not accurate at all lol. Fan comes on at 207F exactly, (viewed with scangauge II) use an infrared temp gun and it’s 200F at the sensor and 203F at the metal heater pipe.
I’m leaving it alone as coming on early isn’t gonna hurt anything.
I recently flushed the coolant and changed to a 180* thermostat and have OBD fusion. Everything is good but I was thinking on the way home from work(while watching the temp gauge) that lowering the trigger temp would be an added bit of I surance
Your graph seems to indicate that increased airflow across the radiator offers a huge cooling advantage. How new are the components; radiator, water pump, thermostat? You could interprete the graph to show that higher rpm is driving more coolant through the system. It’s one or the other.
It would be an interesting test to thread a 195° switch into the bleed screw port as an alternative coolant temp switch to supply ground to tigger the fan relay. I’m not sure if that’s an appropriate place to measure coolant temp given the location of the thermostat and the direction of flow but it would be convenient. You might need to use a lower temp switch to accommodate for the cooler fluid at that location. Or find a better spot. Then install a SPDT switch in the dash and reroute the green wire from the ECU to the fusebox through it. Connect the aux CTS to ground on one pole and send the other to the SPDT switch. One position would be the factory wiring and the other would be using the 195° switch to ground the fan control relay instead.
Thanks for the feedback. T-stat is brand new and it is a 180*. Radiator is 20k miles old and in pristine condition. I too am leaning toward the water pump now. On the freeway it drops to 183* and sits there. There have been times that it has dropped to 175*ish, shutting down the t-stat. I also agree it’s airflow related. I have two 9” Hellas on the brush guard and the factory grill. I have a Kalahari grill sitting my office. I just need to get it painted and install. I’m gonna run the same test (house to work) once I get it installed to compare. There’s a lot of crap air has to pass through before it gets to the radiator! Driving lights, grill, transmission cooler , a/c condenser and finally the radiator. I know these have airflow issues but this is crazy
It would be an interesting test to thread a 195° switch into the bleed screw port as an alternative coolant temp switch to supply ground to tigger the fan relay. I’m not sure if that’s an appropriate place to measure coolant temp given the location of the thermostat and the direction of flow but it would be convenient. You might need to use a lower temp switch to accommodate for the cooler fluid at that location. Or find a better spot. Then install a SPDT switch in the dash and reroute the green wire from the ECU to the fusebox through it. Connect the aux CTS to ground on one pole and send the other to the SPDT switch. One position would be the factory wiring and the other would be using the 195° switch to ground the fan control relay instead.
sorry for the double post here but to take it one step further, I could install an additional aux fan next to the factory one and keep it on an isolated circuit where it would automatically come on at 195*
How's the fan clutch? If the A/C is on, the condenser fan will come on at a temp well below 212. Mine comes on around 180 with the A/C on. I also can't for the life of me get my truck to run above 183. That's at altitude in the mountains in the middle of summer going up hills.
02-12-2019, 08:38 AM
