2008 chrysler 300 3.5L radiator fans not coming on

Try a new coolant temp. sensor , signals are sent to the computer and a signal is sent from there to turn them on .

The fans should not run all the time. The way they're set up to come on varies from vehicle to vehicle. Is the vehicle overheating? You'll need to have a scan tool plugged into the vehicle to see what the actual coolant temperature is. Or at least what the computer is seeing the temperature as. Then you should use a laser type thermometer and check the coolant temperature at the thermostat housing. If both readings agree and the temperature is below the threshold for the fans to come on and the vehicle is not overheating I'd say the fans are working correctly. Hope that helps! Jim

The highest I have seen on on obd scanner is 210f. at idle. The needle on the gauge is going to exactly half way or a tad below at idle or after actual driving. Now the outside ambient temp has been in the mid 70's for these scenarios. Michigan weather has not thrown a hot humid day at us yet. I have stood there with the temp that high and have not seen the fan come on at all. Does the coolant temp sensor control the gauge and the cooling fans ? If so it would seem odd that the signal is ok for the gauge but not for the fan.

Also am i seeing that the fans would be on when the AC compressor is running ? If so I have not tried that yet and will go try that .

Yes, see if the fans will come on when the air conditioning is on. Set the controls for maximum A/C, or recirculate. I'd think the fans should be on to pull cool air over the air conditioner condenser that's in front of the radiator. At 210°F the fans might not come on, without the air conditioning running. With the transmission in Park and the engine running step on the gas pedal slightly to bring the engine to about 1,500 RPMs and hold it there. As the temperature gauge creeps up listen for the fans to come on. By the time the gauge is at the 3/4 mark the fans should definitely be on. If they come on and the gauge starts going down, I'd say you're ok. Jim

OK I didnt state that the new fan assembly came about from noticing that the old fans were seized and busted up. Thats why I bought the new assembly. At one time I saw on the OBD scanner there was a cooling fan circuit problem, thats why I tested the fuses and relays. But after clearing that fault it never came back again. And figured that was from running the car without the cooling fan relay in. Last thing i did on it yesterday was disconnect both leads from the battery and clamp them together over night. Today after reading your posts I reconnected the battery and started the car to check with AC on. to my surprise the fans came on when the ECT got to 192 with or without AC on. So Maybe I unlatched something by completely disconnecting the battery overnight instead of just dropping the negative cable. I will report back after some road testing if the problem has not been solved. Thank you for the help gentleman, its much appreciated.

That's awesome. Sounds good to me! You're welcome. Glad to help! Jim