Fan running too often?

{tpc}

Original poster
Member
Jan 22, 2014
359
So recently I have noticed the fan on the tahoe running alot. More than what I want to say normal. The reason I want to say more than normal is because I am noticing it. I did not notice it as much last year. I have tried to shake the conclusion that I have some underlying cause, but I can't shake the fact that I KNOW I am noticing it, where I haven't in the past.

Now the weather has warmed up, so maybe i'm imagining it or remembering "last year" incorrectly. I don't really know.

This is what I do know. Temp is always reading 210 once warmed up. I towed the trailer to ohio and back this past weekend. I feel if I had an overheating problem it would have shown up while towing in 85 degree heat. I know that when you leave the AC on from last drive cycle it will command a fan on when started, and that when you don't it won't. It does both of these things as described.

But what it also seems to do is run much longer than I would expect. Its not like its cycling on and off every 5 min or something. Its like it stays on the majority of the drive cycle. I mean lets say its running hot and the fan comes on to cool it down...I would expect at some point it would have done its job and been commanded off, right?

From what I could figure out on the alldata site, its a dual fan electric fan system. It isn't like the electro-viscous fan on the wifes envoy...which seems to be on its way out...but at least I know what that is. lol

There isn't any codes store or any pending codes. I haven't done anything to the cooling system ever, sans for adding a small amount of dexcool to it prior to the last trip, just to hit the full cold mark on the bottle.

Thoughts? Am I crazy? Air bubble in the system maybe? (though without ever doing anything not sure how that happened) T-stat or coolant sensor on its way out?
 

Sparky

Member
Dec 4, 2011
12,927
I noticed on mine it doesn't take much time at a stop for the fan to fire up. I really don't have a sense of normal to base off of though.

How long has it been since the coolant system has been flushed out and coolant changed? I know on my old car when the coolant got old it also got a bit gunky an it got some partial clogs. Flushed the system and it helped a lot.
 

{tpc}

Original poster
Member
Jan 22, 2014
359
Besides the power steering fluid, its the only thing that hasn't been changed in the past year.

Last year I had the brake fluid changed. This year I've changed both diff's, transfer case, and trans fluid myself.

Is it worth it to bring into the dealer to change the coolant? Should I get a coolant "flush"?

What about the power steering? Is that a might as well do it type of thing? What would one do? Suck the old crap from the reservoir? Or let the dealer handle it?

I've tossed a good amount of money at this thing lately, all in the name of general maintenance, in the hopes of trouble free miles ahead for a bit. But like any older car, little things keep popping up. I just want to drive it now lol.
 

Sparky

Member
Dec 4, 2011
12,927
You could just do the coolant yourself. Drain it and refill it with fresh dexcool. Or you could get some radiator flush, follow the directions on the bottle, then drain/refill with new.

Power steering is a pain to do as you have to suck it out, top off with fresh, circulate system, rinse and repeat over and over until it is changed out. Or, just wait until something blows and leaks all over like my Trailblazer. Empties the system out so you have nothing but fresh when you get it fixed lol.

Could just have an independent shop do both if you want, doesn't have to be a dealer.
 

{tpc}

Original poster
Member
Jan 22, 2014
359
If its not a bear to do, I'd probably just do it myself. As for the power steering...I'll wait for the hard sell from the dealer next time lol.

The only thing is you can't get all the coolant out of the block, right? Guess I have some more research to do.

But if you just drain and refill, will that get any gunky stuff out? Hate to think there is any in there in the first place...
 

Sparky

Member
Dec 4, 2011
12,927
You don't get all the old out as some may linger (unless you flush with water over and over) but you'll still be 99% new and fresh.

You're right, a drain and refill won't really get much gunky stuff out if there is some in the system. Probably better to use that flush stuff if you suspect there may be gunk in there. If it has original coolant then that is 8 year old stuff in there, and it wouldn't be too surprising if it has gotten a bit yucky.
 

Mooseman

Moderator
Dec 4, 2011
25,262
Ottawa, ON
For the fans (just so we're all on the same page, you do have e-fans), do you run the A/C or defrost a lot? The fans will run to cool the A/C. The A/C will run with the defrost or defrost/floor to remove moisture when the outside temps are above freezing. You can't turn it off on those settings, which is why I avoid them unless I really need to defrost the windshield.

Apart from that, if the engine temps are good, I wouldn't worry. The PCM controls them well (wish I had them!). I drive the same Tahoe at work and I hear the fans on a regular basis. It's still a good idea to change the coolant.
 

{tpc}

Original poster
Member
Jan 22, 2014
359
Thanks for the replies. So probably will change the coolant. But just for fun, on the way home I hooked up the torque app and tried as best I could to monitor the fans. Yes they are the e-fans as far as I know.

Anyways, while driving the temp as reported by torque was running at 192 most of the time. On occasion when I got on the e-way I saw temps as low as 188. The outside temp was 55f the whole time. Now during the stop and go traffic, it would routinely get up to about 195, at which point I think I heard a fan turn on, very faintly. At one point, the temp jumped up to 199 and I know I heard the fan at the point, and the temp quickly went back down to 192 in a minute or so.

The odd thing was I wasn't doing anything special when the temp spiked to 199..in fact I think I was idling along in the stop and go traffic.

I can only imagine that when the outside temps are at 85 or above, the fan would run often, as I think that high a temp might induce more "above 195" type behavior.

Does this sound typical of the thermostat? Or maybe I have a t-stat or temp sensor starting to flake?
 

Mooseman

Moderator
Dec 4, 2011
25,262
Ottawa, ON
Sounds normal to me, maybe a touch on the cool side at speed. Quite normal that the temperature would spike a bit in stop and go or idling and the fans come on.

Now quit worrying :smile:
 

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