No high speed cooling fans?

[dpollak81]

Hey it’s been really hot here the last few weeks and noticed that the Denali A/C is struggling anytime we are stopped and won’t cool down when you first start it till you get moving.

Checking it out yesterday and I don’t think the high speed on the cooling fans is engaging. if I remember right if you start it after it’s been sitting in the sun in a 100 degree day, the fans sound like a jet engine if you have the A/C on.

The fans are spinning but quiet…. I know GM on many rigs did a right fan relay and left fan relay then a high speed relay but I can’t find a high speed relay anywhere.

Any ideas on where to start?

 

[Doubeleive]

the fans on the k2xx are different than previous generations, I don't think there is a low/high relay they are a brushless motor so they can turn at any speed on demand

 

[dpollak81]

Oh wow didn’t realize that. So what would trigger the high speed? It seems like the fans should be drawing more air while sitting.

It had the previous condenser replacement around 65k that was required on all these models.

 

[Doubeleive]

Oh wow didn’t realize that. So what would trigger the high speed? It seems like the fans should be drawing more air while sitting.

It had the previous condenser replacement around 65k that was required on all these models.

it depends on the coolant temp and the ac demand, I have seen a couple people have a coolant temperature sensor issue but I think in both cases the fans were running high speed pretty much all the time, you would have to google for the technical reasons the fans would be put in high speed mode and then try to replicate that and see if the fans respond properly. you could try cranking the ac up and do high speed run down the highway for a couple miles then pull over real quick and check to see if the fans have kicked up high? if it's not overheating then it's probably fine.

 

[dpollak81]

I've read a ton about the fans staying on and the faulty temp sensor.

Maybe it needs a recharge or has a small leak then... I just can't find much information as to why the fans wouldn't kick on into high speed. they kick on and off with the A/C on and off if I test that with the engine being cooler.

I'll see if I can get the engine good and hot and see if it will kick onto high speed then. The hard thing is that even in HOT HOT temps the engine stays at 200-210.

 

[gooffeyguy]

When I remote start mine on a 90-100* day the fans kick on and are loud, but they're not on high. After a couple minutes, usually about the time we're getting in, they do kick to high though.

 

[dpollak81]

When I remote start mine on a 90-100* day the fans kick on and are loud, but they're not on high. After a couple minutes, usually about the time we're getting in, they do kick to high though.

Yeah ours don’t seem to sound like they are spinning to fast…. When we remote start now and let it sit for a couple of minutes the air is not blowing cold. It’s just barely cooler…

 

[Tahoe14]

Like you said possibly low on freon, could be the condensor issue that many have experienced and there is a TSB.

 

[dpollak81]

Well got Mjolnir back from the shop and seems like all components were working fine but it had about half the refrigerant in the system it was supposed to. Supposed to have 2lbs and it only had .96 lbs… They leak tested it and no leaks so not sure what’s going on there so we’ll keep an eye on it.

Works great now that it I has the correct amount of refrigerants and the auto setting is much more chill now that it can keep up.

 

[CTUBS8732]

Did that fix your issue with your fans?

 

[CTUBS8732]

I’m having this exact same issue. I just replaced the whole cooling fan relay fuse block with a fresh one cause the original had burnt prong ports. Thought I had solved the issue when I found out the ground was mounted in a bad spot due to shotty repair by body guy so I regrounded to a better spot.

Now I have your issue going on at the moment and noticed the bottom left relay on the bottom left port is burnt.

Fans magically turned on high mode then never did it again. I’m stumped on this one.

 

[Doubeleive]

I’m having this exact same issue. I just replaced the whole cooling fan relay fuse block with a fresh one cause the original had burnt prong ports. Thought I had solved the issue when I found out the ground was mounted in a bad spot due to shotty repair by body guy so I regrounded to a better spot.

Now I have your issue going on at the moment and noticed the bottom left relay on the bottom left port is burnt.

Fans magically turned on high mode then never did it again. I’m stumped on this one.

this is a different generation, everything is different fan wise. my 2012 fans go on high and you can hear them well, never hear the fans on my 18
I assume you are talking about the nbs, you might want to inspect the fan motors and harness connectors and see how they look I had one that started to short and melted the connector a little bit and quit working until I bumped the harness. replaced the motor and harness connector and they work good again.

 

[CTUBS8732]

Mines is 2005 Tahoe. Usually the fans are on high as soon as I start the truck with the AC on. Now high mode never kicks in even if the truck is idling for an hour. It ain’t overheating but also ain’t no cold air coming out the vents, just cooler than outside air. Refrigerant level is good.

 

[CTUBS8732]

When driving it’s cold

 

[CTUBS8732]

Changed temp sensor now only one fan spins in low mode and the other kinda spins. Prior to replacing, both wouldnapin in low mode. Only rear ac blowing how it should. Refrigerant is good. I'm stuck in a rut with this one