Hi all,

Been trying to figure out this issue for awhile, the symptoms basically is, when driving on the freeway with AC on after a long period of time the needle jumps up like a mark above normal, if im pushing it, the needle will jump up again another tick then another one shortly the more I push it, but in town and in stop and go its fine and the needle doesn't move from normal, now obviously something was wrong and I pinpointed to the thermostat, went to the pic a part and grabbed me another thermostat from a junked TL, did the boiling pot test and it worked as should, so I pulled the thermostat that was in the car and did a test on it and well it barely opens up so that explains why, fluids weren't keeping up while on the freeway, I put the better thermostat in the car and bled the system drove around and all is well, noticed today when commuting back home it went up AGAIN but it took a lot of load with AC on for it to even do anything I even put a little more abuse to it and the tolerance was significantly better than before I even did some back to back WOT runs in this heat and wouldn't even budge, just happens on the highway with the AC on

My question is, is this normal for this needle to jump a mark or two with AC on in this blistering heat? We are talking Vegas heat 108-112ish, If not would a brand new thermostat be much better? (Im assuming it'll open up much wider) also Im sure we have some owners from AZ and I'd like their input or any very hot enviroment.

Looking forward for some feedback thanks.

Where the needle sits is where it usually is, yellow mark is where it'd go as described in this post

 

Im sorry I meant to add to this "with additional load such as overtaking on the freeway and very slight grade change(slight going uphill)"

 

Temp gage doesn't give out exact reading on coolant temp, they either tell you the car at cold, operating temp or over heat. If you want to see the real data get a OBDII scanner with live data and you will see actual coolant temp read out in real time. I would not worry about the temp gage jump a notch or two do to the heat lately in the southwest US and yes if your engine load increase with A/C on and going up a steep hill your car coolant temp would jump.

 

How old is the coolant in the system? It should be replaced every 7 years with the Blue Honda Type 2 fluid.

I'd wager that the bad thermostat coupled with a dirty radiator is causing the slight rises in temp. Small amounts are no big deal, it's when it starts climbing and does not come back down that you have an issue. The only time I got a 3G TL hot above the top of the temp symbol (1/4 inch from H) in my experience was on a track day and the car was not prepared at all, not a smart decision....

 

Thank you

Sorry I forgot to mention brand new radiator and new coolant Honda Type 2

However all is well tbh, this heatwave does take a big toll but I appreciate the responses, so far so good