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Hey guys. I'm a newbie hear and i've seen that there are a lot of overheating threads but i have another one. I just purchased a 1990 Corvette and i was driving around town tonight. Its about 90 degrees out and the engine temp jumped up to probably around 240-245. That was driving between 20-35. When I turn the air on, it jumps to 250 or just a tad below the 260 line. Any ideas on what could be wrong? Thanks for any suggestions
 

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When you kick on the A/C, the fans should come on and bring the temp down. Your temp goes up? Are your fans turning on at all? With or without A/C?
 

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Sounds like you need more air flow. Make sure both cooling fans are working " If your car has two " Check for junk blocking air flow through the condenser and radiator. Check air dam " If it's broken or center section is gone it will cause much higher temp at higher speed. And check to see if the thermostat is working correctly. My 1988 vette has a 180 stat hypertech chip that turns on the primary fan at 175 degrees and I installed a switch to turn on the secondary fan any time I want it on. I can cruise through town on a 90 plus degree day with the air on and never see more 215 degrees:thumbsup:
 

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Sounds like you need more air flow. Make sure both cooling fans are working " If your car has two " Check for junk blocking air flow through the condenser and radiator. Check air dam " If it's broken or center section is gone it will cause much higher temp at higher speed. And check to see if the thermostat is working correctly. My 1988 vette has a 180 stat hypertech chip that turns on the primary fan at 175 degrees and I installed a switch to turn on the secondary fan any time I want it on. I can cruise through town on a 90 plus degree day with the air on and never see more 215 degrees:thumbsup:
:agree:

I'd either take it somewhere and have the radiator power flushed or flush it yourself ASAP! You can buy the stuff to do it yourself but most of the quick oil change places do it.
After you check the fans to make sure they are all working I'd remove the radiator shroud and clean between the AC condenser and radiator.

Those temps are way to hot. I think the specifications are 260 absolute max. You might blow a head gasket or crack a head if those temps stay up that high for any length of time.

Good luck!
 

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im fighting the heat battle too. but my front air dam is missing, so thats most likely my main problem. I flushed the radiator and the engine block at the same time I was replacing the thermostat. ( a lot of poo came out ! ) when flushing radiator there is still junk built up inside the engine block, and the thermostat will not allow it to circulate unless you remove it and flush the engine block at the same time. I installed 160 deg thermostat until my new front air dam arrives

I agree with the inspection and cleaning of the ac condencer and radiator cavity behind the shroud. mine was dirty as heck. just be real careful not to damage the lines. I realley like my ac in south fl. :D

as for the coolant, I do not use any antifreeze. if you go to pepboys they sell this big gallon tin can of coolant additive , much like watter wetter, but it specificly is designed to work with only water. and it has better cooling properties than antifreeze / water mix.

after doing said above my ride is driving around town at less than 210. averaging somewheres around 200. wich was a drastic improvment from the 225 / 230s it was running at before

now I have a question for you guys, :
I only have one fan. its a puller behind the radiator. and its wired to come on when I start the car ( even if the car is cold ) but I never hear the fan kick on to high. I think its just hotwired to run on low speed always?

can someone put a digital test meter on their fan when its on low and high and post us the numbers its powered at for both? because id like to run a switch to manualy turn high power on my fan but dont know where to start. and knowing the power it needs on high will tell me where to begin.
 

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I didn't think my fan's have a high and low speed. They always sound the same.
 
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