Fans run like the engine is overheating, coolant gauge reads no temperature, A/C disengaged.

[Terry2015Tahoe]

My 2015 Escalade was running fine, but I noticed a loud hum under the hood. The fans were running much faster than usual, so I looked at my coolant guage and it was reading zero, despite me having driven for miles. I pulled over and under the hood the temp felt fine, hose barely warm to the touch, even the heat shield near the exhaust manifold barely felt hot.
I did not think much of it, then I received a message saying the A/C was shut down.
I got home, shut of the engine, but the fans were running at high speed and continued to do so, as if it was overheated, and needing additional cooling.

Being late at night, I didn't want the fans to drain the battery overnight, so I disconnected the battery. I called the dealership, and they said it sounded lie a sensor malfunction, or maybe the thermostat was stuck. For my Corvette, I know exactly where the temp sensor is, as well as the thermostat. On this behemoth, I have no clue where either are located.
In any event I decided to go out and examine the engine. Upon reconnecting the battery, and starting it up, everything seemed back to normal. A/C worked, fans on normal speed, and the coolant temp read a normal temp.

That was a couple of weeks ago, and I assumed the battery disconnect caused a re-boot if you will, and hoped the problem to just be an anomaly.
Sadly the problem started again with the exact same symptoms. This time I let the fans run after turning it off, and they ran for about 5 minutes, then shut off.
Now without a battery disconnect like last time, with a totally cold engine, if I start it up, the fans are going into high speed mode, despite the engine being totally cold. Thus I doubt the thermostat is getting stuck in the closed position, otherwise the engine would overheat.

So with all those symptoms being tied together, I am hoping others here have the knowledge of what it might be?

My 2015 Tahoe did the same thing. Replaced sensor and problem resolved:

 

[exp500]

Vector- I see an awful lot of flowery language as a reply to a minor suggestion of mine. In the end no matter what or whomever suggested whatever, You are gonna do what you're gonna do.
So don't insult me with alot of flowery language that smells like someone shit flowers.

 

[CrashTestDummy]

Why does GM seem to have these things happen? Like the crap motor mounts and dash panels on the NVS Tahoes, to this stuff?

I JUST had this happen on our new-to-us 2018 Tahoe. Bringing my bride back from cataract surgery I noticed that the temp gauge was reading below 160 degrees and the fans were going, and continued to run after turning the engine off in the garage, all while keeping us quite warm on the drive home in 50-degree rainy weather. Parts have been ordered, but damn!

 

[CrashTestDummy]

Well, that was quite the PITA! We rolled the Tahoe out to the shop today to do the temp sensor replacement. While you can see the radiator drain plug, you can't touch it without significant disassembly of the front of the truck. Checking with the FSM, on hopefully the quickest route to accomplish that, they have you use the special GM vacuum tool J23834, or whatever it is, or you're on your own if you want to use gravity and that drain plug. Additionally, the FSM notes that the temp sensor is on the front side of the driver's head just ahead of the exhaust port. there is NOTHING there! The temperature sensor is exactly where the video posted earlier in this thread showed with the guy's Escalade.

After pulling the front of the passenger inner fender well liner, then pulling the front grill area cover and then trying to remove the grill, we opted for the redneck method of pulling the old sensor, sticking a finger over the hole in the intake and then jamming the new sensor in place and tightening it down (15 lb-ft, according to the FSM). After stuffing towels in front of and behind the sensor, we quickly got the sensor replaced, and then went back to putting all the other crap we'd pulled off back on. We probably lost a cup of antifreeze, and dropped nothing on the shop floor. Started the truck and the fans still spun up. After checking that we did indeed have a temperature reading now, I cleared the code and the fans turned off. A test drive to the grocery store revealed no new surprises. Hopefully, we're good for a while.

 

[dmad1]

My 2015 Escalade was running fine, but I noticed a loud hum under the hood. The fans were running much faster than usual, so I looked at my coolant guage and it was reading zero, despite me having driven for miles. I pulled over and under the hood the temp felt fine, hose barely warm to the touch, even the heat shield near the exhaust manifold barely felt hot.
I did not think much of it, then I received a message saying the A/C was shut down.
I got home, shut of the engine, but the fans were running at high speed and continued to do so, as if it was overheated, and needing additional cooling.

Being late at night, I didn't want the fans to drain the battery overnight, so I disconnected the battery. I called the dealership, and they said it sounded lie a sensor malfunction, or maybe the thermostat was stuck. For my Corvette, I know exactly where the temp sensor is, as well as the thermostat. On this behemoth, I have no clue where either are located.
In any event I decided to go out and examine the engine. Upon reconnecting the battery, and starting it up, everything seemed back to normal. A/C worked, fans on normal speed, and the coolant temp read a normal temp.

That was a couple of weeks ago, and I assumed the battery disconnect caused a re-boot if you will, and hoped the problem to just be an anomaly.
Sadly the problem started again with the exact same symptoms. This time I let the fans run after turning it off, and they ran for about 5 minutes, then shut off.
Now without a battery disconnect like last time, with a totally cold engine, if I start it up, the fans are going into high speed mode, despite the engine being totally cold. Thus I doubt the thermostat is getting stuck in the closed position, otherwise the engine would overheat.

So with all those symptoms being tied together, I am hoping others here have the knowledge of what it might be?

Just fixed the same on my2017 Tahoe last week. It is the Coolant Temperature Sensor located next to the thermostat housing. Just unplug it by mashing the tabs on the side and take it out with a 16 mm socket (might have been a 19mm). My fans would not shut off until it cooled down about 10 minutes before I did this. Bought replacement at Autozone for around $20. Good time to go ahead and replace the thermostat but they are around $50 or so.

 

[sb38646]

Well then tell me why even come to a forum like this, when the only two suggestions is to do what is obvious to most other people.
If this was a very active forum, someone might give such responses as a bump post to bring it back up to the top some someone with knowledge might see it.
But this forum seems like it is not frequented that often.

Yes I can go to Google or Youtube looking for answers, and at one point found something similar on another GM type of vehicle. Yet I had hoped to come hear to see if other fellow forum members who had the same type of engine I do (6.2 in the Escalade and Denali) might have some experience with this same issue and/or advice.

When I see a fellow poster asking for advice/help with something I know about, I take the time to give detailed advice or relay my personal experiences.
Not just say look it up elsewhere.
Yet to some it sounds like a robo bot could just come into every thread, and give a generic recommendation to "check the owners manual, Google the problem, or go look at Youtube videos for help".
Again, if that is the case, why even be a forum member and post here?

BTW - Though I have not fully figured out the issue yet, my ESV threw a code, and Autozone said it is (with their limitations) the thermostat.
Assuming it matters to anyone the code thrown was [ P0128 ] Coolant Thermostat (Coolant Temp Below Thermostats Regulating Temperature)

My 2015 tahoe is doing this. I have been resetting battery and can go a week before it happens again. I recently had therm. Sensor replaced. When replaced it was not currently experiencing the problem as i had reset battery 2 days prior. Well one week after replacement, i am back to resetting my battery. i have read the forums and watched youtube which mainly says sensor what could my problem be ???

 

[Atesekunz]

No offense is intended with the following reply to your post.

Many of us do not need generic replies about checking factory manuals, or that we can buy information from Ebay, or Google is our friend.
When I see fellow posters who need assistance, if I have the ability to help them, I give as much information as I can.
I do not tell them to "read a manual" or "go to the dealership" as some non-informational reply.

In this case I am hoping a fellow forum member has experienced the same problem, and can give advice, so I do not make a generic mistake on what be a commonly experienced problem.
If anything, the most annoying reply to a members posting of their bad experience, is a fellow member asking "why didn't you ask here first, before spending $$$$ that should have only cost you $.

So thanks for your reply.
That said, I am looking for suggestions from those who might be familiar with this issue.

I had the exact same symtoms... i replaced the temperature sensor ...it didnt work correctly...then i disconnected the battery for over 30 minutes...reconnected battery...& EVERYTHING began to work correctly including dash water guage. There is a reply that doesnt send you to manuals or other research without personal hands on information shared.

 

[Rygrego]

Default for a malfunctioning temp sensor is fans full on, just in case.

 

[jcf1967]

I had seam exact problem. After a long drive, turned off the truck and the fans were in overdrive and the gage was pegged at 160. Turned truck on and off, same result. Next disconnected the battery to stop the fans and left off for several minutes (hoping for some kind of reset). Connected battery and started truck. Temp started to increase. Drove for long time and never went above 180 (used to always be 210). Replaced thermostat - problem fixed...

 

[Lbi2000]

My 2015 Escalade was running fine, but I noticed a loud hum under the hood. The fans were running much faster than usual, so I looked at my coolant guage and it was reading zero, despite me having driven for miles. I pulled over and under the hood the temp felt fine, hose barely warm to the touch, even the heat shield near the exhaust manifold barely felt hot.
I did not think much of it, then I received a message saying the A/C was shut down.
I got home, shut of the engine, but the fans were running at high speed and continued to do so, as if it was overheated, and needing additional cooling.

Being late at night, I didn't want the fans to drain the battery overnight, so I disconnected the battery. I called the dealership, and they said it sounded lie a sensor malfunction, or maybe the thermostat was stuck. For my Corvette, I know exactly where the temp sensor is, as well as the thermostat. On this behemoth, I have no clue where either are located.
In any event I decided to go out and examine the engine. Upon reconnecting the battery, and starting it up, everything seemed back to normal. A/C worked, fans on normal speed, and the coolant temp read a normal temp.

That was a couple of weeks ago, and I assumed the battery disconnect caused a re-boot if you will, and hoped the problem to just be an anomaly.
Sadly the problem started again with the exact same symptoms. This time I let the fans run after turning it off, and they ran for about 5 minutes, then shut off.
Now without a battery disconnect like last time, with a totally cold engine, if I start it up, the fans are going into high speed mode, despite the engine being totally cold. Thus I doubt the thermostat is getting stuck in the closed position, otherwise the engine would overheat.

So with all those symptoms being tied together, I am hoping others here have the knowledge of what it might be?

Coolant Temperature Sensor. A very easy switch out and you won't lose much coolant at all if you clamp all the hoses going in/out of the waterpump next to it and the thermostat and do it when its cold. It sounds like the classic issue of the coolant temp sensor not giving any reading to ECM and the engine runs the fans high because it thinks it could be overheating and cannot tell. Good luck.