i have a 2013 f150 ecoboost
when going to start the truck up the cooling fan comes on (high). it stays on high til you shut the truck off.
any ideas what to look for?

 

That's kind of surprising. How are your temperature gauges behaving? Is your air conditioning or defroster on?

 

truck not even running?
but when driving everything is good, too cool out to run the air, and defroster is off

 

just by turning the key on the fan is on

 

Is this a recent development? Is the check engine light on?

Sounds like it needs to be scanned for trouble codes and see the data the sensors are showing.

 

no lights on started about a week ago.
its like the temp switch is stuck closed or a relay is stuck,not sure as soon as the key is powered everything on it comes. then you start the truck and its on still.

 

sounds like one of the relays took a crap, shouldn't be too hard to figure out

 

i hope not

 

You really need to connect a scan tool that can tell if the PCM is commanding the fan to run. If yes, you need to look at sensor data to find what's wrong. If no, start looking at relays.

 

Just asking, but is your truck tuned or still on the stock programming?

 

My truck is all stock

 

Check your A/C components. If the pressure switch does not reach pressure regardless if the A/C and/or defrost is on the fans will continue to run on high. If there is an issue with the clutch/or compressor may cause this as well. Unplug the A/C and check to see if hte fans run at a lower rate.

 

Does the outside temp sensor have the proper reading? It's not on the fritz is it? I've noticed my outside temp sensor directly affect how fast my condenser/radiator fans run (when the A/C is on). I believe, even when the HVAC in the truck is set to the defrost/heat (blend) the compressor is called for (if the outside temp is not too cold).

Hope you figure it out.

 

I pulled the relays on thr fans and they stop. Both fans are running makes me think its not the relays. Now i think im going to have to fine the sensor that turns the fans on. But i will have to check the ac yet.

 

The fan can be commanded on by several sensors, which is why you need to see what the PCM is reading. The sensors themselves may be completely fine, and a wiring issue is to blame. You're shooting in the dark.