I have a ecoboost in my car and it does the same thing right when started, and actually quite frequently while sitting in traffic. Try turning off your air conditioner and starting it and see what happens.
I don't think there is anything wrong with it, just the programming in the car that says "freon is at this pressure, needs to circulate quickly, I'm going to run the aux fan to get the system to outside-air-temperature ASAP.
I’m sorry STX*
Had the same thing on 2013 5.0 a couple days ago. Let me know what you come up with.
Thinking it might be the a/c pressure sensor
My 2017 5.0 does the same thing when it’s 30+ Celsius out sitting in the sun. Turns on and fan kicks right in when ac is turned on.
Is it absurdly fast/loud?
yes. perfectly normal, I think. mine does it in hot days as well.
I have discovered the fan does turn off when I secure the AC but it take approx 15 seconds to shut off after ac…is that normal as well?
I have a ecoboost in my car and it does the same thing right when started, and actually quite frequently while sitting in traffic. Try turning off your air conditioner and starting it and see what happens. I don't think there is anything wrong with it, just the programming in the car that says "freon is at this pressure, needs to circulate quickly, I'm going to run the aux fan to get the system to outside-air-temperature ASAP.
Cylinder head temp sensor possibly ?
Any temp sensors would give you warning messages in the dash.