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I just replaced the heads on my 96 Impala SS for a set of Corvette factory Aluminum heads. The engine runs great, lots of power. However, when I sit at idle the temperature gauge climbs to one tick mark below red before the passenger side fan comes on. Is that normal? Also, I was told that the primary fan is supposed to come on whenever the A/C is on, but on mine it doesn’t happen. My A/C system is not charged, could that be the reason for the fan not coming on when the A/C is on? I replaced the thermostat for a new 160 degrees as well as the two relays and the sensor by the water pump. Any assistance will be greatly appreciated.
Qdawg
 

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The factory fan on temps are pretty high on these, so that does sound fairly normal.

The swap to the Corvette heads was a waste of time money and effort and if your butt is telling you otherwise it is wishful thinking. I am sorry to answer your first post that way but it is the truth.

Depending what year they are the Camaro/Vette heads are a good foundation for porting but in stock form they are NOT an upgrade. The Vette had different intake tract, cam and high octane tuning that all made a bigger difference in power than the head design.

If you want the car to run cooler at a stop you need to have the pcm reprogrammed by someone like PCMperformance.com they can do other stuff too like firmer shifts, some power gains in spark and fuel reprogramming.

Please ask before you do anything else to the car because there are a LOT of bad products with good names on them in the market, and a lot of things people think they need to change where stock is actually very good.
 

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The passenger side fan is the primary fan. It kicks on around 220* or so. The secondary will kick on at around 230* or so. The fan will kick on if the A?C head pressure reaches a certain amount. I don't remember what these thresholds are.
 

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One tick mark below the red is where my secondary fan comes on, found that out when my pri. fan quit. My primary comes on at a hair above the halfway mark. All stock, 180 T-stat.
 

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I am having the same issue of neither fan coming on. We have figured out the the ac being under charged is at least part of the issue. We figured this out by using a jumper wire on the compressor sensor and the fans will stay on until they reach a certain temperature.
With this little trick I can drive it now at least, I just have to turn on the ac at every stop light.
 

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How long have you had the car? If the pcm can trigger the fans based on AC it should have no problem doing so based on temp.

As I said 7 years ago the fan trigger temps are pretty high and a LOT of folks mistake that for not functioning, and at 20yo I bet a lot of pressure caps have failed and are letting cars boil over before the fans are ever turned on due to the 224/242 fan temps.
 
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