Radiator Fan activation temperature

[BrandonMods]

I was curious if anyone knows if there is an OEM document out on the interweb or a website with information concerning the radiator fan activation temperature? If not could using an led in series with the radiator fan relay work to determine activation temperature?

[Baltothewolf]

It varies from vehicle to vehicle. Yes you can, it's extremely easy.

[BrandonMods]

what value resistor do you place upstream of the led is my question then, or is the draw so small that you do not have to worry about the led exploding? Also would I have to use a scangauge to get the exact temperature of activation?

[Baltothewolf]

Originally Posted by BrandonMods

what value resistor do you place upstream of the led is my question then, or is the draw so small that you do not have to worry about the led exploding? Also would I have to use a scangauge to get the exact temperature of activation?

Not sure about the resistor and yea, an ultragauge is also an option at 1/2 the price, I have a UG and I prefer it over the SG personally.

[oldtamiyaphile]

If you have a SG you can tell when the fan is running by watching the engine temp. Engine gets hot> fan comes on> temp back to normal. The fans come on on both my Fiat and Renault at 93*C, if the temp is below that, I know the fan's not running. It basically never runs.

[BrandonMods]

I was kinda bummed for that exact reason that my car does not have the digital option for coolant on the DIC :/

[spacemanspif]

I'm guessing it's somewhere around 210-220. Factory stat should be 190 so the manufacturers give the fans a little time before cycling on; turning on at 200 would have your fan running constantly.

[nemo]

Originally Posted by BrandonMods

I was curious if anyone knows if there is an OEM document out on the interweb or a website with information concerning the radiator fan activation temperature? If not could using an led in series with the radiator fan relay work to determine activation temperature?

On my car (06 GP 3800 Series III L26. ) the operating temperature range 194 to 225. The cooling fans with the air off won't come on until the temp reaches 220 degrees then turn back off at 197 degrees via the u gauge. So the below information seems accurate for the 3.1L or 3.4L V-6 Engine (VINs J, E - RPOs LG8, LA1)

The PCM commands Low Speed Fans on under the following conditions:

Engine coolant temperature exceeds approximately 106°C (223°F).
A/C refrigerant pressure exceeds 1310 kPa (190 psi).
After the vehicle is shut off if the engine coolant temperature at key-off is greater than 140°C (284°F) and system voltage is more than 12 volts. The fans will stay on for approximately 3 minutes.


The PCM commands High Speed Fans on under the following conditions:

Engine coolant temperature reaches 110°C (230°F).
A/C refrigerant pressure exceeds 1655 kPa (240 psi).
When certain DTCs set.
Engine Coolant Indicators
Engine Coolant Temperature
The IPC illuminates the engine coolant temperature indicator when the body control module (BCM) determines that the coolant temperature is greater than 123°C (253°F). The BCM receives a class 2 message from the PCM indicating the coolant temperature. The BCM sends a message to the IPC via the class 2 requesting illumination.

Engine temperature - Car Forums and Automotive Chat

I believe the factory thermostat is 195

[ksa8907]

1998-2004 LH cars (intrepid, lhs, concorde, 300m) fans came on low between 216 and 223 depending on a/c usage and engine size.

[BrandonMods]

The temperature sensors on act as thermoresistors do they not? If so wouldn't it be possible to used the resistance value or voltage drop across the coolant temperature sensor to figure when the relay for the radiator fan will open?