Cooling fans always running?

cbrsilv15 · December 6, 2016

My truck just started this morning. Remote started and the fans came on and wouldn't stop. 30* outside so it's not warm here. Went out and turned it off and then started it again. Fans came on the whole trip to work. Has anyone had this issue before on these trucks? I have 42k on it so it's not covered under warranty otherwise I would just take it to the dealer.

Dnt · December 6, 2016

Yes I had some strange issues with the cooling fan on my old 2014 5.3. The fan would come on at unexpected times and run for a good bit of time when i knew it was totally unneeded. Was intermittent and the dealer said waaaiiiiiit for it................. NORMAL

cbrsilv15 · December 6, 2016

I changed my headlight bulbs last night and had to unplug the maf sensor, but I never started it when it was unplugged. I know some guys get CEL when they do that. Just weird.

Did it ever affect anything long term with your fans intermittently running like that?

Dale_K · December 6, 2016

I'm only guessing but it might be due to the A/C operating. Pretty sure the truck will automatically turn on the A/C to defog the windows.

cbrsilv15 · December 6, 2016

It has never done it before. It has never done that even in the hot mid 90* summer we had. I thought the trash truck was outside my house because it was so loud.

I was planning on unplugging the MAF and disconnecting the battery for 30 mins or so, but the fans never came on when I came home from work. Very strange.

truckguy82 · December 8, 2016

I changed my headlight bulbs last night and had to unplug the maf sensor, but I never started it when it was unplugged. I know some guys get CEL when they do that. Just weird.

Did it ever affect anything long term with your fans intermittently running like that?

Mystery solved

I unplugged my maf the other day to spray maf cleaner on it. Truck was off and I let it sit off for 2 hours.

When I started my truck and drove to my destination, fans were running full tilt on a cold engine on a cold day. It was strange.

I guess it has something to do with unplugging the maf. Odd GM programming, that's for sure.

cbrsilv15 · December 8, 2016

I hope that's all it is. Lol. Glad you had the fans come on after unplugging the maf so we both have some knowledge now.

My truck has been fine ever since.

silveradosid · December 10, 2016

if you forget to tighten the clamp after the maf sensor and it sucks in air it put the fans on lol learnt the hard way

cbrsilv15 · December 10, 2016

It was tight. I made sure it was tightened on my airaid tube.

Dnt · December 10, 2016

You know what that jogs my memory the stupid fan on thing happened after I changed the air filter each time on the 2014 and I unplugged the MAF sensor connector to make it easier to pull the intake hose cuz I did not know at the time that it would affect the computer.

I just recently put a CAI on my 2016 and it specifically said in the instructions DO NOT UNPLUG THE MAF SENSOR I guess it causes a lot of things to have to reset? Dang Boy Live and Learn.

ksag · December 13, 2019

I have a 2014 5.3 and the fans come on extremely high, the temp gauge drops to 160. When you cut the motor off the fans continue to run on high speed until the timed power cuts off. Took it to the dealer they said it was because mu AC was out which does not make since. The dealer said oh ya it most likely do to that, so $1500.00 later for a new condenser and 2 weeks later they are doing it again!! Got to be a rheostat or thermal coupler. You can drive 30 miles stop and put you hand on the motor and it ice cold!

silveradosid · December 15, 2019

this problem can be caused by the a/c. i found this problem on a 2015, the fans were always running on full speed. he bought the truck used and thought it was normal , but the a/c didnt work. i hooked the gauges up and the system showed full charge. i hooked my scannner up to see the a/c pressure switch was commanding the fans on high. i was going to replace the pressure switch, but found the wiring going into the switch was bad, fixed the wiring and problem solved

William Johnson · January 23, 2020

On 12/13/2019 at 2:01 PM, ksag said:

I have a 2014 5.3 and the fans come on extremely high, the temp gauge drops to 160. When you cut the motor off the fans continue to run on high speed until the timed power cuts off. Took it to the dealer they said it was because mu AC was out which does not make since. The dealer said oh ya it most likely do to that, so $1500.00 later for a new condenser and 2 weeks later they are doing it again!! Got to be a rheostat or thermal coupler. You can drive 30 miles stop and put you hand on the motor and it ice cold!

Did you ever figure out why this was happening? I have a 2014 and it just started doing the exact same thing. Fans come on full blast as soon as I crank my truck up and they stay on well after I cut it off. I'm baffled!

nicks2014sierra · February 6, 2020

Me to any updates?

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Sha2014 · February 12, 2020

The other thing is watch the volt gauge. Mine is dropping to almost 10/11 when stopped. We checked the air filter so I unplugged the MAF. I was able to get my fans to stop running at high speed once I cycled the key on and off a couple time and wiggled the MAF back and forth. Hopefully it stays working properly! I have a 2014 Silverado with 79k miles.

Edited February 12, 2020 by Sha2014