3 New Fan resistors fitted on Ford 2016 but they still keep blowing???

As long as you have documentation of having filled a legitimate claim during the warranty, they would have a legal problem with you if they later try to deny you a warranted repair.

Thanks Hornet, it's just frustrating not knowing what is causing the problem in the first place...

Even with the warranty they are wasting your time repeatedly bringing it in for service. I think this is your work vehicle and it doesn't make money sitting in the repair shop. I think the problem may actually be in the heater blower motor. If that motor is drawing too much current, the resistor will be overloaded, running hot and burning out. The Motorcraft part (resistor) is available at $135 and I see a cheap aftermarket part for $18 at Rockauto. Also note that this resistor comes into play only on the slower settings and is bypassed on "High". If you can feel the heater motor running too hot to touch, then I would consider having them replace it at their expense, and I bet this problem will be resolved. Repeatedly getting the same results tells me it's time to try something else. Hope they can resolve this for you. Just remember: FORD= Fix Or Repair Daily. Lol

Thanks Hornet, love the acronym for FORD! I will let you know the out come, many thanks for your help, I will suggest the new motor.