How do I check if my high speed fan is coming on?

The Green GT said:

I know its supposed to come on with the A/C, but will it come on even if the car is not even heated up and you turn the A/C on? like if you turn it on right away?

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Low should come on at ~ 208*F. Is it doing this? This takes care of most of the cooling needed. From the factory, high comes on a ~228*F . Not something you really want to *test* out in its true dynamic.

The fan does indeed come on when the AC is on, no matter the motor or ambient temps. E.g., if you use the defroster setting in the winter, even if it's freezing out, the fan comes on ASAP.

Good luck.

If you have a code reader, just plug it in and the first thing that will happen is the fan will cycle both low and high speeds for a couple seconds. You should be able to hear it clearly. This should at least tell you if both circuits are operational. It seems that for me, I can't hear the difference in fan speed for normal and max A/C. My fan wasn't turning on in traffic for the past month and the engine was running really hot, then I swapped out the temp sensor and everything works great now. The old sensor had pretty much an open circuit, no resistance, nothing, hence no fan.

And just for the mix of diagnostic stories (in case it helps someone), I had the same response as 1TMF when I ran codes (low and high cycled). However, in its dynamic, high would not come on with Max AC turned on. I got it back as far as the computer being what was not switching from low to high.

Can someone answer me this: I've seen posted and even read in the manual that MAX AC should make high come on. WTF wouldn't high speed come on for normal AC. In both situations, the AC is working just about as hard (I think max is even more efficient since it's cooling previously cooled air). I never understood the logic there.