when car idle coolant goes to 200+ degrees

[N9QGS]

Hi guys,

This may be completely normal, I just never noticed it maybe until I had a ScanGauge hooked up. But when I am sitting at a traffic light or just in park sitting ideling, I notice the temperatures goes from 184 to 200 in about 2 minutes and after 200 it clicks the fan on and drops the temperature down to like 196, and then within a minute it does this again.

However this is the weird thing, they say if your car is running hot to turn the heat on. as an experiment, when the car gets up to 198, I turn the air conditioner on max cold. (this should not be as effective as the heat, maybe should have a negative effective but....), it instantly drops the coolant temperature back to 184.

I dont have an explanation for this, its like when you turn the air on, the coolant circulates better and cools, vs at idle and A/C off.. Is there something going on that I should be concerned with? I checked my coolant level its to the top.

Im thinking maybe there is air in the system. But if you guys think this, would I just again take the radiator cap off and run the car for 20 minutes with the heat on, is that right?

Ron

[CTScott]

Hi guys,

This may be completely normal, I just never noticed it maybe until I had a ScanGauge hooked up. But when I am sitting at a traffic light or just in park sitting ideling, I notice the temperatures goes from 184 to 200 in about 2 minutes and after 200 it clicks the fan on and drops the temperature down to like 196, and then within a minute it does this again.

However this is the weird thing, they say if your car is running hot to turn the heat on. as an experiment, when the car gets up to 198, I turn the air conditioner on max cold. (this should not be as effective as the heat, maybe should have a negative effective but....), it instantly drops the coolant temperature back to 184.

I dont have an explanation for this, its like when you turn the air on, the coolant circulates better and cools, vs at idle and A/C off.. Is there something going on that I should be concerned with? I checked my coolant level its to the top.

Im thinking maybe there is air in the system. But if you guys think this, would I just again take the radiator cap off and run the car for 20 minutes with the heat on, is that right?

Ron

There are a few things that the ECM does differently when the AC is on, including running the fan whenever the compressor is running.

[YarisSedan]

Any car that sits for awile will start to overheat. Even a brand new car. The radiator pulls the heat off the engine and as you drive the air cools it and the coolant cycles back through the engine to pull out more heat. If you are stuck in stop and go traffic on a hot day ofcourse there is no air circulation which is why the cooling fan kicks in at a certain temperature. Looks like our car is set at 200.

So to answer your question this is 100 percent normal

[Bluevitz-rs]

I've seen mine as hot as 220°F on really hot days in traffic. And it's been up to 230°F on the track. But I also have a 1.3bar TRD rad cap to raise the boil point of the coolant a few more degrees.

And turning you A/C on will only make the car run hotter in the end. The heat from the refrigerant get cooled from in front of the rad, so the fan has to pull the heat through the rad. So if you're ever really stuck, yes putting the heater on is the best way to help cool the car down.

[127.0.0.1]

100% normal. 202 to 224 can be normal on hot days stuck in traffic

only worry when you get the idiot light on the dash. then u have a problem with heat

[Yaris Hilton]

The AC cools it just because the fan's running all the time. The pressurized coolant boils at something over 250°F. You're not overheating at all. The engine runs a bit more efficiently at higher temperatures.

[90tsi]

i dont remember exactly how many or the lil math formula but for every pound your pressurize fluid at you raise the boiling point so many degrees.... like salt in a pot water.

[N9QGS]

OKay I appreciate it, like I sad its been in the 50's and It can creep up stopped at a long traffic like to the point the fan kicks on (200), and I just thought it was odd that turning the air on would being it back in check, never been in heavy stop and go traffic, just a random light shortly after driving the car for 10 minutes that day or after 2 hours on the highway and coming up to a light it does it, I wont pursue it. but now that I know the fan is coming on then I know why its cooling down. and that Im not at a high level even at 200 degrees to be concerned with, so Im glad to hear those reports. Glad to know after 135,000 I still can't find anything to repair on the vehicle besides my normal maintenance items. hahaha