High engine temps only when AC is on - Pontiac Solstice Forum
 
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post #1 of 7 (permalink) Old 08-17-2019, 11:06 PM Thread Starter
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Recently I have been getting high engine temps but only with the AC on. The coolant gauge will read 189-194 without actually and will go as high as 232 with AC on. Driving around will keep the temps between 219-225. But once stopped like in traffic it will go up to 230. The weather outside is hot and this is the first time I have driven this car in the summer. Temps here are around 100 to 111 most of the summer. Which leads me to believe that it might just be the weather in my area. At night it will only go as high as 214-216 with AC on. The fan seems to be going full speed whether the AC is on or not. It is setup to start the fan at 100% at 200 degrees with hp tuners.

Last edited by Vasquezz1228; 08-17-2019 at 11:13 PM.
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post #2 of 7 (permalink) Old 08-18-2019, 06:51 AM
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Do you have an auto or a manual? If you have a manual do you allow it to coast down in gear? If not, you should. And since you know how to tune, make sure the FCO (Fuel Cut Off or sometimes refered to as DFCO). Basically what it does is shuts the fuel off to the cylinder during "coast down" in gear. This rapidly cools the motor. Also, don't be heavy footed in traffic and make sure to blip the gas occasionally (every 45 or so seconds if you are stuck in traffic) if you have a manual, this keeps the coolant flowing.

All of these cars have an issue running AC while sitting in traffic and keeping the motor cool. I don't care if they're stock or not...the little 2.0L (I'm assuming you have a 2.0L because you talk about tuning) with the turbo have no chance at staying cool in city traffic...especially when temps outside are over 100+ degrees, let alone with the AC on. The motor just has to work too hard to turn the AC compressor.

The above works for me, but rarely does it get above 92 here in Detroit...and rarely do I drive my car when it gets that hot because when I use the AC it gets worse gas mileage then my Charger Scat.....

My advice: Put a "cooler" thermostat in the car. I think the OE is 185 degree...I'd go to 150 degree if you could find one! Or if you are only driving it in 100+ degree heat all the time, you might consider pulling the thermostat all together. I don't recommend that, but seeing as how you said summer is 110+ all the time...I don't think it would hurt too much. And I'm not certain if a much cooler thermostat is available. Maybe someone can weigh in on the pros/cons to pulling the thermostat altogether in a hot climate like this.....

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Last edited by The_Ghost; 08-18-2019 at 06:57 AM.
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post #3 of 7 (permalink) Old 08-18-2019, 08:47 AM
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Based on your entire description I'm not sure that you have a problem. This seems mostly like a case of needing higher temperatures to transfer more heat. I have seen temperatures in the 210 range on a 95 degree day, and what you are seeing is simply proportionally higher water temperature to achieve the same differential across the radiator.

A colder thermostat isn't going to make any difference. That trick works for autocross and drag racing because the duration of the higher heat loading is relatively short and the lower initial temperature allows the absorption of quite a bit of heat before overheating. Once you heat soak everything it doesn't matter because the thermostat is completely open anyway.

I would make sure that there is nothing obstructing airflow through the radiator, and maybe even wash it. You could have some air in the system, so purging it wouldn't hurt.

While 232 is higher than I would like too, you are OK up to 240. What does it do under load at high speed with the AC off?

Is this new behavior? Changes in something like this tend to be a warning. Have you changed anything in the car? When was the tune changed?

It might be worth trying to hold the idle a bit high to see if the temperature decreases, but I don't think it will. Unless the water pump is not functioning properly you should have adequate water flow.

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post #4 of 7 (permalink) Old 08-19-2019, 11:00 PM Thread Starter
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Ghost my car is Auto unfortunately and I have DFCO enabled. I wish we had more options for it on the LNF ecu because it stops below 40 MPH. I feel a bit better knowing that mine is not the only car with these issues. John is right, a lower temp thermostat will not help but thanks for the suggestion.

John, mine would also see temps around 210-214 around 95 degree weather. I'm pretty sure now that it's just the weather. I changed the timing chains and HP fuel pump. Bleed the system like a YouTube video from rpm Motorsports showed. The temps didn't start going high until the start of 100+ degree weather. The tune was done back in January when I got the car and only made changes for the 3 bar map about a month ago. I tried holding the idle higher the other day but it will be the same temp or go a bit higher. Like I said it doesn't go over 232 but I am not used to have any car with such high coolant temps. I usually shut the AC off when it hits 225 and let it cool down a bit before turning the AC back on.
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post #5 of 7 (permalink) Old 08-21-2019, 02:27 PM
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Quote:
Originally Posted by Vasquezz1228 View Post
Recently I have been getting high engine temps but only with the AC on. The coolant gauge will read 189-194 without actually and will go as high as 232 with AC on. Driving around will keep the temps between 219-225. But once stopped like in traffic it will go up to 230. The weather outside is hot and this is the first time I have driven this car in the summer. Temps here are around 100 to 111 most of the summer. Which leads me to believe that it might just be the weather in my area. At night it will only go as high as 214-216 with AC on. The fan seems to be going full speed whether the AC is on or not. It is setup to start the fan at 100% at 200 degrees with hp tuners.
That's an interesting problem because usually turning on the AC is what is recommended for a high coolant temperature condition. The reasoning behind this is that the condenser fan comes on and pulls more air through the radiator. Of course if you're sitting in traffic it might help to increase the RPM a little to get the coolant moving. I would also check that the thermostat is opening completely. A thermostat designed to open at a lower temperature is not the cure, because the temperature is being exceeded anyway. Maybe simply replacing the thermostat with a new one of the correct temperature will fix this if the thermostat in the car is not opening completely.

Let us know.
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post #6 of 7 (permalink) Old 08-21-2019, 02:56 PM
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Originally Posted by halnwheels View Post
That's an interesting problem because usually turning on the AC is what is recommended for a high coolant temperature condition. The reasoning behind this is that the condenser fan comes on and pulls more air through the radiator.
We only have one fan, and his is already on. Running the AC is just adding more heat to the coolant.
Quote:
Of course if you're sitting in traffic it might help to increase the RPM a little to get the coolant moving. I would also check that the thermostat is opening completely.
He tried that. It didn't help
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A thermostat designed to open at a lower temperature is not the cure, because the temperature is being exceeded anyway. Maybe simply replacing the thermostat with a new one of the correct temperature will fix this if the thermostat in the car is not opening completely.

Let us know.
Correct, except that the engine cools normally at lower ambient and when the AC is off.

John
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post #7 of 7 (permalink) Old 08-21-2019, 08:03 PM
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As JohnWR said, turning on A/C will never help an overheat condition. The coolant temperature will already be commanding the highest fan speed to control temperature, and the condenser (typically in front of the radiator) will be delivering hotter than ambient air to the radiator. You may be able to turn the heater to full heat and high blower to alleviate an overheat, essentailly creating an auxiliary, small radiator via the heater core.

To look at this differently, modern vehicles are calibrated to disable the a/c compressor based on coolant temperature, I think Kappas are somewhere around 250, too long ago for me to recall specifically. So if you are still getting A/C operation, you haven't reached the danger zone relative to coolant temperature, so keep on drivin'!
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