2016 F150 3.5L

Electric cooling fans started running on full blast from the time I start the truck until I shut it off. Even when it's 20 degrees out and the motor is cold.

No check engine light.

All else seems normal except around the same time the fans started running non stop, my average mileage dropped from 20.something down to 18.something. the cooling fans are electric so I don't see how they could affect mileage, but the timing is sure suspicious.

Any techs here? ...or anyone else have this problem with their F150?

Find the relay that controls the cooling fan. The fuse/relay panel diagram is in your owner’s manual. Swap it with another relay of the same ampacity that is known good. Start the truck with a cold motor and if the fan does not come on, the relay is stuck “on”. If it’s stuck on, replace it.
That’s the first thing I would check.

TECHNICAL SERVICE BULLETIN
Poor A/C Performance And/Or Engine Cooling Fans Running Continuously 21-2250
01 September 2021

Model:

Ford
2015-2020 F-150
2017-2020 F-Super Duty
2018-2020 Expedition
Lincoln
2018-2020 Navigator
Issue: Some 2015-2020 F-150, 2017-2020 Super Duty and 2018-2020 Expedition/Navigator vehicles may exhibit poor air conditioning (A/C) performance, loss of airflow and/or engine cooling fans running continuously from high A/C pressures. This concern may be from the evaporator freezing up due to the evaporator temperature sensor being biased. To correct the condition, follow the Service Procedure steps to replace the evaporator temperature sensor.

Action: Follow the Service Procedure steps to correct the condition on vehicles that meet all of the following criteria:

Found on Roads Dead....

On my 2014 F150 with the 5.0, the cylinder head temp sensor went bad. Dealer had the truck for two days and couldn’t figure it out.

Usually electric fans are triggered by a temp sensor...

Common on the 5.0 f150s. I don’t know about the 6cyls.

I'm going to do this every time an F-150 is mentioned, get mad if you want to

This fella’s handy to have around.

Yeah, but you're the only one that read, that supplied correct answer, Mike !!

😂
Hence the quote.

Laffin' !

First
On
Race
Day

Hell get a Chevy and a truck bed full of replacement lightbulbs. Or just drive in the dark but you’ll be styling. Every make has its troubles. People drive what they like. Everything else sucks.

Cracked
Heads
Every
Valve
Rattles
Oil
Leaks
Every
Time

Fix
Or
Repair
Daily

Must
Own
Pickup
And
Rope

Speed kills- - - -buy a Chevy and be safe!

Pontiac?
👿

Poor
Old
Nagger
Thinks
It’s
A
Cadillac

Or:
Requires
A
Mechanic

First on race day

As Ironbender pointed out, you're sure handy to have around. Thanks 99, Im gonna try replacing that Evaporator Temperature Sensor, and see if that does the trick.

Cheers Mate, any time !!

I would think that the relay wouldn't click on unless there was power coming from the sensor. There shouldn't be any with a cold engine.

The solution to that problem identified by the TSB is one that I'm sure would be very, very hard to find by a normal mechanic.

And the people who animate for King of the Hill have absolutely no idea what an engine compartment looks like. Sheesh.

That’s not necessarily true. Relays can stick. The sensors provide the signal for on and off. The power to run the fan is not the same conductor as the signal conductor. Otherwise there’s no reason to have a relay.

Yep, only knew about it because, we've had 3 though the shop since fall & o1 of my tech's is ford trained.

**To prove out, hook up a/c gauges to check pressures - the high side will be "through the roof".

Any real mechanic should know the fan is triggered by a temp sensor..