Coolant temperature fluctuations normal??

[Jman2]

Thanks for the feedback. I was thinking it could be air in the system, but I feel like the temp readings would be more erratic(?). Also, not sure about this but it just makes sense in my head… if the thermostat wasn’t opening and closing at the right time, wouldn’t the temp reading bounce back and forth on a constant basis? I was thinking fan as well, since the fluctuation happens during specific driving parameters… do the fans kick on at certain speeds or temps? I also noticed today that the temp SEEMS to be more stable with the ac running. Not sure if it’s in my head or not, but it seemed that way when driving today

 

[Marky Dissod]

... thinking fan as well, since the fluctuation happens during specific driving parameters ... do the fans kick on at certain speeds or temps?
I also noticed today that the temp SEEMS to be more stable with the AC running. Not sure if it’s in my head or not, but it seemed that way when driving today.

'05 Electrical fan settings. If AC works properly, it lowers coolant temps a wee lil bit,
'cause 'Fan 1' is nearly always on if the AC is on and builds at least 220 psi.
'Fan 1' is 'Low Speed. 'Fan 2' is 'High Speed'.
Note how hot the 'High Speed' coolant threshold is.

If those temps are too hot for you, get tuned.

 

[Jman2]

'05 Electrical fan settings. If AC works properly, it lowers coolant temps a wee lil bit,
'cause 'Fan 1' is nearly always on if the AC is on and builds at least 220 psi.
'Fan 1' is 'Low Speed. 'Fan 2' is 'High Speed'.
Note how hot the 'High Speed' coolant threshold is.
View attachment 443150
If those temps are too hot for you, get tuned.

So based off of those fan settings, what I’m experiencing is normal? That would be awesome if that’s the case, because I was about to try to chase something that may not be an issue?

 

[Fless]

Does your 2004 Yukon even have electric fans? I think those engines still had the clutch fan.

If it does have electric fans, they are likely not OE, so you might want to verify that your fans are coming on correctly at around the specified temps.

How many miles? Is the radiator the original one?