2017 Expedition Cooling Fans Loud. On High When A/C is on.

[NickC31]

So I am getting annoyed and so far have not found a permanent solution. After start up with A/C on usually a few seconds later my electric cooling fans will kick on super hi mode. Sounds like a semi-truck. Very loud fan noise. They are working properly just kicking on in a seriously high mode. So I have heard the thermostat can be the culprit. Before I went to change that out. I thought to clean the evaporator coils on the radiator with foaming degreaser cleaner then rinse off. I noticed that this kept the fans from kicking on in that high mode and get extremely loud. My coolant levels are good. I had a flush and fill. A/C recharged. No codes. Why would me cleaning the radiator fan allow the fans to be much quieter? This is not the fix cause after few hours the fans kick back on high mode and annoyingly loud again. Does anyone think that could be cause of a faulty or bad thermostat? Or something else like an expansion valve?

 

[Speedboosted]

My fan runs on high with the AC on when ambient temps are in the 90s or higher. Pretty normal to ensure everything is staying cool. These motors produce a lot of heat so it needs to work harder compared to other cars to keep everything in check.

What are the ambient temps when this happens?

 

[purevw]

Chances are that it's not engine temps causing the fan to go to high. It's more likely the A/C condenser temperature or pressure. If you are sitting still with the A/C running, it's quite normal, especially if the A/C fan is set to high and on fresh air rather than recirc. Washing the coils serves to cool the freon in the coils, so that is a Band-aid. In short, the colder you have the A/C thermostat set and the higher you have the climate fans set, the harder the A/C has to work. When the ambient temperature is high, recirc makes a significant difference in how hard the system has to work. I would be far more worried if the fan was failing to cool the coils. It's a large loud fan because it's a high capacity A/C unit with a lot of cubic feet to cool. Much like in a house, setting the thermostat to "all the way cold" serves no useful purpose other than causing unusual strain on the system. Set it to a reasonable temp and leave it.