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Running 220degrees with A/C on



Temp was 85 today. Turned on A/C and watched temp. rise to 220. To date, I had radiator recored to a 4core,changed water pump. Fan seems to be ok. Is any one else running this hot???
Temp Gage OK ?

I run my air quite abit. In traffic it may push the 200 degree mark, but usually runs around 190 to 195. I have a stock L81 with 2 1/2 exhaust and flowmasters as the only engine/hp mod. 4-speed.

Temp. gages or Temp sending devices have been know to be off, have you check temp with an external device?

Good Luck, and keep us updated with your findings, Lots of people will be curious, esp. with the CORVETTE SUMMER coming ;)
Make sure you have a good quality thermostat.If it is stuck open it will sometimes allow the coolant to flow thru the raditor to fast for it to cool. Chuck

I had my AC upgraded to the newer system and it makes the temp rise to 240!
So, I have AC, but I dare not use it!
Here in GA I think I'm gonna need it, so I am looking with interest at these posts! I will try changing out the thermostat. Radiator was recently given the fine-tooth going over.
Too HOT!

Roy: 220+ is something to be concerned about, especially here in Florida.

I had the same problem and the cause was very strange. I checked to see that the electric cooling fan was working, I reverse flushed the cooling system, changed the thermostat, checked ignition timing and checked the water pump. It still was running 220. Went to automotive electrical specialist and he found the problem. Although a visual check of the electric cooling fan showed that it was working, it really wasn't working properly. An electrical meter indicated that it was drawing too much current and not running at full speed. We replaced the electric cooling fan motor and wa-la it was fixed! now temperature back down below 200.

BTW a quick way to check the electric cooling fan is to turn on your A/C, that turns the fan on full time.

I would like to add a auxiliary electric fan to kick in when temp reaches 200 degrees. Has anyone done this??
Aux Electric Fan

Roy: The only time an aux electric cooling fan will help is when the car is not moving. Normal airflow through radiator when car is under way should be sufficient to keep temperature normal. If you want to install an aux electric fan there is a adjustable sending unit with a probe that inserts through the vanes of the radiator. I purchased one about a year ago at Advanced Automotive (formerly Western Auto).
Hi Al
Can you please tell me the size of the fan and where you mounted it??
Roy: What actually happened was that I was replacing the fan temp sending unit in the engine block and it broke off in the block. Thinking this could turn into a big problem trying to get the unit out and because it wasn't leaking, I opted for the aftermarket adjustable sending unit that mounts on the radiator. I used the existing electric cooling fan and everything woked well.
I don't get the panic. Why is everybody so worried once the temp passes 200 F ?
The 79-82 Vette auxiliary fan only came on at 238 F !!
Even this temp must still be in a safe designed limit.
I have a 68 BB convertible bored and stroked to 454 CI.
with headers and sidepipes = hot.
In slow traffic, it sometimes reached top indication ( 240 ) and I had to stop the engine.
I installed a original 79-82 temp switch into the R/H
head and connected a auxiliary fan fwd of the water
cooler. Seems to work this way .
Just my way of thinking using GM figures.
What the book says


I agree that 220 is not a panic temperature. but it is attention getting and concerning. We all know that water boils at 212, that's why the cooling system is pressurized, so the coolant doesn't turn to steam (gas) above 212. There is a limit even in a pressurized system. You are right about the electric aux fan sending unit. the book on my 86 L98 states that it kicks in at 239, and mine does. I found the difference is that 239 on my temp gauge and the actual engine temp (external gauge reading) is below 220.

The real concern is that an overheated motor will crack heads, engine blocks or gaud pistons to the cylinder walls (major problems). And now with aluminum heads it doesn't take a lot of heat to warp them.

When your car begins to run hotter than normal it is an indication that a cooling problem is begining to develope.

All I'm saying is pay attention to what's going on under the hood while you can do something about it. That's why I hate idiot lights..... when they come on it's too late!

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