Rad fan kicking into high non stop

Electric radiator fans are engaged via the vehicle's computer system. There is a temperature sensor somewhere on the vehicle. On one of my vehicles it is located on the Thermostat housing, your's can be elsewhere. The fan is designed to click on when the sensor detects the engine is over heading. It sends a signal to the vehicle's computer which turns on the fan. If the sensor is defective it could send an overheat command, thus causing the fan to become active. On some vehicles, disconnecting the electrical connection to the sensor will cause the fan to stop.

Thank you for the response, I have another 5.0L truck, I'm gonna locate the engine temp sensor and try swapping them and see what happens.

Put 2 cans of 134a freon in it. I was having the same issue for about 3 weeks. Ford charged $520 for a $50 fix.

If you can, check the pressure on the high side of the ac system. If you need a manifold set, they’re only about $25 on Amazon. If the pressure on the high side is staying high but staying low or normal on the low pressure side, you probably have a clog in the system or a bad expansion valve. Hope this helps

With the temperature sensor, would the vehicle show the correct temperature on the dash?

I have a 2011 F150 with a 3.5 ecoboost. I am loosing antifreeze by the gallon and nothing seems to be wet. I cannot find anything that appears to be leaking or broken.

Jerrett, did you find the cause?

Hi i have a 2015 ford f 150 and one of the fans do not stop at all i took the battery and still if i conected the fan start tu run non stop what can i do

GuruYF68H is that $520 Ford wanted to charge is because of them saying the low speed fan ain’t working anymore so it’s cause the high speed fan to kick on?

2012 f150, same issue here. Fixed it. I have been researching this issue for two years. These parts that I replaced were mentioned as fixes for some vehicles. I fixed them myself. Replaced a coolant reservoir hose, did have a minor drip, both upper and lower rad hoses, and the high pressure switch for the ac. None of these fixed my high fan speed. I read a lot of people replacing the expansion valve, and it fixing the problem. I wasn’t ready to bleed the system down until it was my last option. I ordered the expansion valve online and saved it for several months. I finally started to have cooling issues in the cab. I talked to a mechanic who is a family member, and we vacated the system. Vacuumed it down, and noticed a small release of the vacuum. We put 24ozs of Freon in and the high fan speed stopped running high speed. So I waited till the next day went to his shop which was 90 miles away. The ac worked great on the way there. Vacated the system down again and removed the expansion valve. Here was an underlying problem, we removed the first bolt, then the two torx bolts. The second bolt was not tight at all. The weight of the ratchet spun it loose. It was a factory oem part. It had signs of the green dye leaking around the valve. This could be an issue with more vehicles. Loose bolts. My observation only. Pulled a vacuum again and it held. 24 ozs of Freon installed, and no more high fan speed. Now, in the past I had to put Freon in because of low Freon, possibilities of adding too much, probably. Who hasn’t. But, I believe the underlying issue is with the expansion valve on most vehicles. Faulty install from factory and possibly a defective part. Like I said two years of reading forums of defective valve. I am not a paid mechanic but I am a do it yourself mechanic. I enjoy working on my truck. I have gauges, vacuum pump, and all the tool necessary to fix it. I hope this helps you with your crazy fan speed. The forums of research I have read, payed off. Just wanted to return what I learned to you. Good luck.

I had a bad water pump in my 2013 F150, 5.0. The shop changed the water pump, radiator hose, and thermostat. Ever since, my fan has been running full blast! I unplugged the wiring to the A/C high pressure sensor but the fan kept running! Everything else according to the shop checked out! The fan still comes on even at 70 mph in 25 degree temps! Read somewhere that the problem could be the thermostat, if the replacement wasn’t oem. That will be what I look into next.

Jaredline, Did the new OEM thermostat fix your problem?

My 2016 f150 has been under warranty and the Ford dealership said my fans stay running like that because that is the way they've designed them but no other truck runs at high speed like mine I've take it to several other people and they say there's nothing wrong with it but the air conditioner quit working and the fans run high took it back to Ford they bled the system recharged it and the fans went off 3 months later the fans kicked back on we took it back to Ford and they said that's just the way it's supposed to be so here's what I did it's still not fixed but it has something to do with the high side if I take a pin and I push down on that all there is that's in there is air once liquid starts coming out then the fans stop immediately so there is air getting in somewheres and I don't understand it it's not Freon it's air I know that Freon supposed to be in there but if that's not what it is so what's going on here somebody tell me

Hey Lm5858 I’m dealing with the same problem with my 2016 f-150. It first happened December 2019 I took back to the dealership and fixed the problem temporarily. The diagnosis was the ac high side was 425psi low 50. They tested the system recharged it and replaced the ac evaporator expansion valve. It worked fine for 9 months same problem fans not shutting off and no ac. But this I had to use a different dealership and now I’m out of warranty their diagnosis I have a bad ac compressor and I have to pay for it. That’s bull I think they trying to scam me. How often does ac compressor go bad under 50,000 miles. Hope that help you out a little.

My 2016 F 150 had the same problem with the radiatorfan running all the time. I took it to my dealer and they replaced the expansion valve. Problem solved !!

Same problem. 2012 5.0 liter xlt 4x4 crew cab. Changed water pump and thermostat. Toyota had a routine to burp out air pockets nose high as possible at different angles with truck running and res cap off. I tried that. I did get the coolant to drop from fill line by running the truck and squeezing bottom hose. And it seemed to shut the fan off after topping it off and warming engine back up. I dont think my thermostat was OEM and have read that was a fix for a few.

HELLO, FOR THE FAN RUNNING ON HIGH ALL THE TIME. CHECK YOUR FRION LEVEL, I JUST FIX A 2016 F150 WITH THE SAME PROBLEM AND I RECHARGE THE AC SYSTEM IT WAS LOW AND EVERYTHING WHEN BACK TO NORMAL. CHEEERS.

2014 5.0 l. I changed water pump and thermostat. Afterwards after driving for 20 min high speed fan cam on. Never came on before ever. After searching I changed the NAPA thermostat rated for 187f to the Ford motorcraft 190. It’s all good now. As funny as it sounds it actually “smells” cooler.

2011 F150 5.0 Had all my coolant lines and thermostat replaced due to big coolant leak issues. After the fix my fan kicks on and stays on once coolant is to temp. Dash meter shows stable temp levels that are where they should be. Fan stays on until I turn truck off. No leaks and fluid levels are fine.

Does anyone know if the Coyote 5.0L thermostat is 170 degree thermostat?

2016 f150 2.7lt. Fan stuck on high Changed with factory thermostat ..NO change I Drained the AC system right down to 0lbs. I Left it for 30mins to empty I Recharged it again .. and everything works good again. Fans haven’t kicked on

Help just put long tube headers on my 2011 mustang gt guy that did it broke the AC suckion hose put new one on got AC top up and now fan runs all the time??????????