i recently noticed that my aux fan is almost always on. as soon as i turn the car on in the morning, the fan comes on (without the a/c being on). sometimes it does go off, but then it comes right back on a minute later. i had my codes scanned last week for a different issue and they're the ones that pointed out the fan issue to me. they showed me that the ECU was being told that the coolant was like 230 degrees even tho it was cold 60 degrees outside and the engine was cold. i already changed the coolant temp sensor and that didnt help at all. i know there is a relay for the fans in the ECM box, but what other sensors play into this issue? is there any other sensor, other than the coolant temp sensor, that tells the fans to come on? and can you tell me where they are locates as well. thanks

 

coolant temp doesnt control condensor or aux fan, the climate control head does. the control head does use the coolant temp sensor as an input, but thats it.

i'd see what the climate control head sees the coolant temp as...and have them go from there

 

Well does your ECU still think the engine coolant is still always hot even after you replaced the sensor. If so, id check the wiring.

 

i dont know, i havent gotten mu diagnostics scanned again to see what the readings are. i realise the climate control unit manually commands the condensor fan on when you turn the A/C on, but the control unit is turned off. so if its not powered up, how can it command the fan to turn on? i know it also comes on when a signal is sent to the ECU saying that the engine is hot and it comes on to cool off the engine. so i'm wondering what sensor sends that signal...if its not the coolant temp sensor, then what sensor is it?

 

Well its both, im pretty sure its the ECU and the coolant temp sensor for a hot engine, and the climate control unit if the A/C is on. Its most likely the coolant temp sensor and the ecu to blame. The first step would be to see if the new coolant sensor is working corectly.

 

yeah i know, but the place that scanned my codes last time is 30 minutes away and its just annoying driving that far to get my diagnostics scanned and everywhere closer than that wants to charge me 30 minutes labow which is just BS.

 

PM me your VIN and i'll look it up for you.

and just cause you power it off doesn't inhibit its rest functions cause it still recieves power from the ignition

 

PM sent

 

i'm looking up all the controls for your aux fan...

 

You have one mechanical fan and one electric...?

Starting backwards from the fan.
Goes to J101 (Second Speed Relay)
and J26 (Coolant Fan Relay)

F18 / F54 Coolant Fan Control Thermal Switchs controls the ground for both these relays.

And power to the thermal switch comes from the A/C control head.

So I would pull fuse S42 (40amp) Fuse No. 19, See if the fan goes off. Then pull S51 (5amp) Fuse No. 21 and see the same.

Then find and pull the relays one at a time and see which one cuts the fan off, and let me know