Why is my radiator fan so loud… anyone else?

My radiator fan kicks into high speed about 20 seconds after starting the truck. The temp gauge looks normal, coolant is topped up, but the fan keeps running full blast.

Has anyone had this happen before?

What year is your truck? My 2014 did the same thing, and it turned out to be a bad thermostat. It never overheated, but that was the issue. My mechanic also mentioned that a bad AC pressure switch can make the fan run on high all the time.

@Franz
2012

Just had to fix this on my 2013 F-150. No check engine light, but when I scanned it, I had code P1288-00. It turned out to be the cylinder head temperature sensor that controls the fan. There are actually two sensors—one for the gauge on the dash and one for the fan. The fan sensor was the problem and needed to be replaced.

@Fifer
I had two different people scan for codes, but nothing came up.

Wade said:
@Fifer
I had two different people scan for codes, but nothing came up.

Do you remember exactly what the part is called?

Wade said:

Wade said:
@Fifer
I had two different people scan for codes, but nothing came up.

Do you remember exactly what the part is called?

Yeah, I’ll send you the part number.

@Fifer
Appreciate it!

Wade said:
@Fifer
I had two different people scan for codes, but nothing came up.

I was wrong earlier—Ford says there’s only one cylinder head temperature sensor, not two. I originally thought there were two.

@Fifer
So the sensor isn’t the issue?

Wade said:
@Fifer
I had two different people scan for codes, but nothing came up.

Here’s the part number from Ford: 9L8Z6G004F. If you’re getting it from AutoZone, the number is SU13514 for my 2013.

Sounds like a bad sensor. You should scan it to see what’s going on.

Tan said:
Sounds like a bad sensor. You should scan it to see what’s going on.

Yeah, I should probably check that out.

Wade said:

Tan said:
Sounds like a bad sensor. You should scan it to see what’s going on.

Yeah, I should probably check that out.

No codes showed up.

Do you have the defrost on?

Harlan said:
Do you have the defrost on?

Yeah, but it still does it even when I turn it off.

Mine did this recently because of a coolant leak near the back of the truck.

Not sure if this helps, but check the transmission fluid level. My son’s truck had this issue, and it turned out the transmission was overfilled. The fan kept running on high all the time because of it.

My 2013 Lariat just started doing this last week. Replaced all the relays, but no luck. Taking it to a shop on Wednesday.

Pretty sure this is normal for these trucks.