"03 LS V8 Fan always on...

[jberbrich]

Okay, my 03 LS V8's electric cooling fan comes on after 5 minutes of diving, even when it is 60 degrees F outside and raining. I had the dealer replace the coolant, put in a new thermostat, bleed the system. I took it in again for a pressure test and a rebleed. No air was in the system and no pressure leaks.

The fan whines so loud that it can be heard at freeway speeds. It sometimes slowly winds down to half speed if I sit and let idle a few moments, like when I get the mail. The car is not overheating at all. Does this sound like a coolant temperature sensor, or a fan with it's own mind, or what? HELP cause I want to give the car to my son before I go to Iraq, but don't want him to inherit a bunch of problems other than coil issues.

Thanks

 

[mlara1129]

i had the same issue on my 03 v8. Had the water pump replaced and my problem was solved. Maybe look into that?

 

[Bullschmidt]

I had a similar problem about a month ago and went through a large ordeal with the dealership I took it to.

My fan also had always kicked on after a few minutes of driving and ran at 100% no matter if it was 0 degrees or 90 degrees outside. The electric fans in genII are variable and should not run as such. The car was not overheating or throwing any codes and had been that way since I purchased the car. Even though it had been serviced a couple of times and inspected with nobody mentioning anything I decided to have it looked at.

Long story short, they replaced my cooling fan which didn't fix the problem. I took it back, complained and they eventually got it right after about a week of trying. They replaced both my cylinder head temperature sensors. No dice. Replaced the thermostat. Did the trick. Luckily I did not have to pay for all the additional parts, labor or diagnostic time. They told me they spent a good deal of time on their Ford hotline trying to figure out what the cause of the issue as they had never seen it before.

Now that I'm done ranting. I'd suggest maybe the CHT sensors. If they fail on either bank the car will read out the engine temperature incorrectly and cause the fan to kick on full lock.

 

[Gus_Mahn]

When mine did the same thing, it was the T-stat.

 

[jberbrich]

Nice ride Bullschmidt. LS's sure look nice. I wish they were as nice mechanically.

Anyway, thanks for advice. I will have the sensors looked into. I already did the thermostat and bleedings that everyone else mentions. It also doesn't matter what the temperature is outside. It could be 60 degrees and raining the fan is on full.

Thanks.

 

[oddball]

Use a code reader to get the real temp while this is happening. If it's staying high (over 200), then it's having trouble cooling. If it stays around or below the thermostat temp (184 f), then the fan is running more than it should. Either the PCM is instructing it to, or the controller in the fan is broken.
Could also be a loose signal wire. The white/black wire controls the speed. If that is loose or flakey, then the fan will run full speed.