radiator fan on full blast for no apparent reason

[yh125d]

2006 fusion, 4 cylinder, 85k

So um, bit of a problem here. Starting just now, my check engine light is on and my fan is going 100 percent from a cold start. Ac, climate control, everything completely off, but the fan is running so hard I can hear it driving down the road. I thought maybe it was low on coolant and the computer told it to run wide open but its topped off. It's never ran that hard before, not even after running it hard with ac on a hot day.

Any ideas? should I be concerned about going to work tomorrow? (50 miles each way)


I hope you guys have something for me in the morning.

 

[LTC8K6]

Temp sensor must have failed. This will cause the computer to run the rad fan wide open because it doesn't know the coolant temp. For safety, if it loses the temp signal, it runs the rad fan at max. Will probably also trigger the malfunction light.

 

[LTC8K6]

One way to check your rad fan circuit, is to unplug the temp sensor and see if the fans run.

 

[Tristicus]

Could be the fan clutch.

 

[deadlyapp]

Could be the fan clutch.

Very few fans have clutches anymore. Most all modern cars have electric fans that are triggered with a relay.

 

[yh125d]

Any clue where the temp sensor on this car is?

 

[bruceb]

Should be somewhere on the Right Rear of the engine for a 4 cylinder engine.

 

[CraigRT]

Either temp sensor or coolant level sensor for sure.

That is classic symptoms of either low coolant or a sensor that has lost it's mind.

 

[yh125d]

Right rear? fuuuuuuu, probably a bitch to get to



Oh well, gonna order one, see what happens

 

[bruceb]

A little more info:

Standing in front of the car, looking at the engine its on the right side of the head or the drivers side. Theres a rectangle looking platform and its underneath that and it screws in from the backside of the head...the frontside should have a hose going to it. ... I think I read it needs a 19mm deep socket to replace it.

 

[Alienwho]

I think my 2001 Jetta has had this same problem for over 50k miles now. Sounds like a Jet ready for takeoff.

 

[JulesMaximus]

Right rear? fuuuuuuu, probably a bitch to get to

Oh well, gonna order one, see what happens

I would plug in a scanner to pull the codes before you go buying parts. It sounds like it probably is the temp sensor but you never know.

 

[yh125d]

argh, fuck


new symptoms. AC not working, not even cool air. Also, it seems weak to start, where its always been strong before. this is only slight though, and intermittent



thoughts?

 

[LTC8K6]

Engine computer probably will not allow the A/C to run without having a coolant temp sensor.

 

[SpatiallyAware]

Possibly bad battery (based on also being weak to start, otherwise it's temp sensor)... It's amazing to see the electrical gremlins that pop up from an almost dead battery

As someone else said - pull the code or have autozone do it for free before buying anything..

 

[LTC8K6]

The A/C adds a lot of heat to the cooling system.

 

[LTC8K6]

The Fusion will turn off the A/C if the vehicle is overheating or in fail safe mode. I suppose the lack of a coolant temp signal may be interpreted the same way.

 

[SpatiallyAware]

Yeah but intermittent weak start isn't from a failing/failed temp sensor..

 

[LTC8K6]

Yeah but intermittent weak start isn't from a failing/failed temp sensor..

Sure. It initially turns on, but then the computer doesn't get a signal from the coolant temp sensor and says "uh oh, I'm overheating" and shuts the A/C off.

Unless I'm just nuts.

Assuming the OP meant the A/C was weak.

 

[LTC8K6]

Yeah but intermittent weak start isn't from a failing/failed temp sensor..

I think you are right, he meant weak cranking. Disregard my comments then and carry on.

 

[yh125d]

New sensor is in. when i turn the key and for a few seconds after start, the temp gauge works properly and i can feel that the ac has started. But after ~5s the gauge drops to off and the AC stops. Im thinking the computer needs reset? I have the battery unplugged so i'll see in about 30 minutes. Am I right thinking that?

 

[yh125d]

Disconnected battery for 40 mins, no change. Got code double checked at o'reilly, still saying temp sensor. Could it be some sort of relay or electrical gremlin? I got the code cleared out and it hasn't come back (yet, 10 miles) but symptoms still the same. No ac, fan full blast, no temp gauge (except the first 5s after key is turned, where gauge and ac both work)

 

[franksta]

New sensor is in. when i turn the key and for a few seconds after start, the temp gauge works properly and i can feel that the ac has started. But after ~5s the gauge drops to off and the AC stops. Im thinking the computer needs reset? I have the battery unplugged so i'll see in about 30 minutes. Am I right thinking that?

I would plug in a scanner to pull the codes before you go buying parts. It sounds like it probably is the temp sensor but you never know.

Why have you not gotten the error code yet? You're shooting in the dark.

 

[yh125d]

why have you not gotten the error code yet? You're shooting in the dark.

rtmft

 

[LTC8K6]

Did you possibly replace the wrong sensor? Often there is one for the gauge and a different one that the computer uses.