I agree I will not always be able to command them on with AC switch but regardless if I removed the AC system from the vehicle the low speed fans should still work off the CTS when it reaches 217* they only come on high speed at 230* faithfully and cool to 225* at this point the fans stop spinning until 230* again. At any point I can provide a ground at the relay and low will work.
I mention AC because when driving that's the first indication the low isn't working it high pressures and shuts down and won't work again until I can get air through it.
I realize the temp gauge isn't exactly accurate but you can obviously see when it's near 230* because it's 3/4 to the top at 200* it's just below half up to just over half. Usually runs around 218-220 on a hot day driving down the road with low speed NOT working when the low speed WORK ( vary rare but I caught it on video to prove at times they do work) it runs around 196-200 while driving with AC on. If it's cool at night I've seen it as low at 183* I have a 180* thermostat in it that came with the new lower intake gasket upgraded replacement kit.
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Originally Posted by brcidd
From my memory, W-cars (as is yours) wait until a/c pressure hits 175psi to turn on low speed fan(s). So just having a/c on is not a test for low speed fan operation- it has to be in hot ambient as well.
Again, the Tech II is the best tool to test with- it will show a/c pressure and fan status- and you can command all fan speeds as well.
Most all other GM cars - the fans come on with a/c request, just not W-cars.
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