I feel your pain as I experienced the exact same issue with my ‘16 Expedition. Last year in April my a/c was intermittent. Took it to the dealership for a diagnosis. They told me it was the blower motor & resistor which was under warranty. However, the blower motor/ resistor harness was not. WTF?!?! The harness was damaged/ burnt pins due to the faulty motor & resistor.
They quoted me approximately $725-750. I politely told them they were crazy. So, told them to do the warranty repair of the blower motor & resistor. I picked up a new harness for approximately $65-70 if I remember correctly. It’s four wires… not hard to wire up at all. I’m a retired Army helicopter electrician/ avionics technician, so I’ve got all the tools and materials to complete the task.
Got it installed and working over 18mos now. I warn against getting an aftermarket harness!!! More specifically AutoZone’s Dorman parts. Got two connectors that had an issue lining up with the receptacle end. In other words, you plug the male/ female end’s together (it was a snug fit) and get nothing. This was because the male pins did not line up with the female receptacles. This happened with the replacement the gave me as well. What drew me to AutoZone was the price; $35. The time spent on my knee’s in the Arizona spring wasn’t fun. Should’ve just used the Ford part from the beginning!!!
Oh, my second issue with a Dorman part was with a MAF sensor for my ‘04 Expedition. Same issue… pins didn’t line up.