Only one radiator fan running

[Merritt50]

2021 Expedition. Recently had the under hood fire recall done. My understanding is this dealt with wiring of the fan and battery Junction box. After picking it up I noticed the fan was extremely loud. Popped hood and the drive side appears to be running wide open and passenger side fan isn’t spinning at all. Took it back to dealer that did the recall and they said everything checked out normal. Everything I read said the fans run in tandem controlled by PCM.

1) should fans always run at same time and same speed?

2) anyone had a similar issue?

 

[99WhiteC5Coupe]

2021 Expedition. Recently had the under hood fire recall done. My understanding is this dealt with wiring of the fan and battery Junction box. After picking it up I noticed the fan was extremely loud. Popped hood and the drive side appears to be running wide open and passenger side fan isn’t spinning at all. Took it back to dealer that did the recall and they said everything checked out normal. Everything I read said the fans run in tandem controlled by PCM.

1) should fans always run at same time and same speed?

2) anyone had a similar issue?

Start your engine (a/c off), open the hood and observe the cooling fans.

If the right side fan is not operating, turn on the a/c. That should cause the right side cooling fan to also run. The right side fan is a variable speed, and the PCM can increase the fan’s speed based upon coolant temperature.

If it doesn’t - there is a problem.

 

[Merritt50]

Started engine (had just been driven home so engine temps were warm) no AC on. For maybe 30-60 seconds no fan ran. Then driver side fan turned on what I believe is full speed. It’s loud. Nothing from passenger. I turned AC on lowest temp highest fan speed and no change. Drive side ran and passenger side not turning.

Everything I’ve read said both fans should operate together at same speed but dealer did not seem to think only one operating was an issue. He explained high / low settings to which I agree but not with only one fan operating… why would you run a fan on 1/2 the radiator?