Radiator fan switch

What are the voltages at the sensor. How mcuh volts you reading at the ground side of the circuit? Do this by back probing each side and telling me the voltage readings

Try swaping fanrelay 1 with 2 if it works off temp then relay if not wiring or PCM. Do both fans come on with AC? Checked fan motor?

Cars computer

I see this question time and time again and 95% of the time, there is nothing at all wrong. These fans aren't programmed to come on until very high temps. It is a 2 speed system and low speed doesn't come on until about 225 degrees. That may seem to hot but it is not and this is the way it was designed to run.

There are several things that might be happening. I would check the alternator. Or have it checked at your local auto parts store. Sometimes they don't put out enough power for everything and can cause this problem.
I would also have a mechanic check the IAC valve (idle air control). This valve is supposed to make the idle go up when these fans come on. You might be able to clean it too.

There is nothing wrong with your computer. You have proven that the computer has control of the fans because they come on with the A/C. I doubt there is anything wrong.

It is usually a fan switch that goes bad, the AC operates off a different circuit.

No, it shouldn't, as I have already pointed out.

Change the fan switch, which activates the cooling fans.

See if you can enlarge this.