It could be a few things. First, the engine coolant temperature sensor (ECT) may not be working properly. Based on temperature, the computer actuates power via a fan relay which allows the fan to turn on. Basically, the PCM provides a ground which completes the circuit. The PCM will actuate the fan relay when the coolant temperature reaches approximately 97 C (207 F) and turns off the fan relay when the coolant temperature drops to approximately 94 C (201 F). If you are not reaching that temp or if the sensor doesn't show that temperature, the fan will not turn on. So, if yo have a live data scanner, see what temperature is being registered by the ECT.
However, and more commonly, the cooling fan relay fails. I attached a picture below showing the relay location. It is in the under hood power distribution box. Check to make sure it is in good condition as well as there are no connection issues.
Here is a link showing how to check the relay:
Here are a few link you may find helpful:
If there is a relay with the same part number, switch them to see if there is a change.
One last thing. Most of these vehicles came with one cooling fan but some do have two. I need to know which you have and if one or both are turning on with the AC. And one last interesting fact. As you already know, when the AC is turned on, the fan will constantly run. Did you know that the fan relay is turned off when the vehicle speed is above approximately 100 km/h (62 mph)? If you are driving above that speed, the fan will not turn on.
Let me know if any of this helps or if you have other questions.
Tuesday, November 5th, 2019 AT 8:38 PM