2007 Yukon Denali overheats and turns off AC...

[Kevin Guines]

My wife's 2007 Denali XL with 143,000 miles went hot and the display showed engine overheating turned AC off. Does anyone tell me what happen and is it an easy fix? I was injured at work, had 2 of 3 surgeries, and don't really have the $$$ to pay the dealer. The suv has been taking care of, this just happened out of the blue...

 

[tsuintx]

First thing you need to check is whether you have coolant in the system or not. If not, then you need to find where it is leaking from and replace the offending item/s.

Kind of difficult to give you a definitive answer as to what happened before you do some investigation.

My wife's Tahoe did the same a few weeks ago due to not having enough coolant due to a leak from one of the heater hose connectors.

 

[kbuskill]

As @tsuintx said... check coolant level.

If it is full I would crank it up and turn on the A/C and pop the hood and make sure both radiator fans are running. If not check your fuses.

If they are then my guess is your thermostat is sticking in the closed position. Very common problem.

 

[tsuintx]

If they are then my guess is your thermostat is sticking in the closed position. Very common problem.

Yup. Had that on my wife's Tahoe, too.

 

[puckhead]

Same issue here. Just flushed the system and changed the thermostat. No leaks either. Overheated again today. I will have to check my fans and fuses tomorrow. Anything else to check?

 

[Doubeleive]

normally there is only a limited amount of things that can occur when this happens out of the blue
and usually in this order or occurrence (in my opinion)
1. there is a leak and coolant is low
2. water pump failure
2. the radiator is clogged up (sometimes chemicals will help but the usual recommendation is to replace it)
4. stuck or sticky thermostat
5. faulty cooling fans or sensor
you will want to check the coolant level first it should never just evaporate, if it is low then there is a leak /or the engine has a internal problem (i.e. blown head gasket, etc)
usual suspect is the radiator, radiator hose(s), heater hose(s), heater t-connector(s) at firewall, or reservoir tank or water pump seep hole.
signs of a faulty water pump is the temperature will be normal when driving and then gets hotter when idling or stopped/this could also be a sign of faulty electric fans as well as a clogged radiator.
I would start from there and see where it leads.....
with a healthy system the temperature should stay normal at all times.

 

[Doubeleive]

I will add that in the past when everything is supposedly working and there is no leak and it starts to overheat I have changed the radiator out with a new one and the problem has gone away, this has happened to me more than once and each time it solved the problem. my recommendation is if your radiator is 5 yrs old or older, yank it and toss it if everything else is known to be good. they don't last forever......

 

[puckhead]

Alright,
1. check for leaks, no leaks.
2. I don't think the water pump is bad but I don't know what to check to see if its bad or not.
3. I just flushed the radiator, don't think its clogged but who knows. Might have to replace it.
4. Just changed the thermostat, good there.
5. fans seem to be working fine.

Hoses are good.

Temperature seems to go up a bit while driving, especially while going up mountain passes. It will die out when stopping at a stop light after this. Usually happens when the wife is driving and not watching the temp. I just need to get this fixed, wife usually has the three kids with her and is pregnant and due the end of this month!!

If I get a new radiator, is there one that is better than stock? I see Mishimoto is a vendor on this site, I might start there.

 

[Warriorpluto]

My temps never go up past 199 degrees. Never seen it go past that and that's in hundred degree Texas heat and an 6.2 engine.

 

[swathdiver]

My temps never go up past 199 degrees. Never seen it go past that and that's in hundred degree Texas heat and an 6.2 engine.

Do you have the K5L?