Erratic fan speed

This sounds like the engine is overheating causing the cooling fan to act funny. Is the cooling system full of coolant?

Here are some guides to help us find the problem:

https://www.2carpros.com/articles/engine-overheating-or-running-hot

and

https://www.2carpros.com/articles/car-is-leaking-coolant

Please let us know what you find.

Cheers, Ken

It is also possible the engine coolant temperature sensor is bad and it is causing the PCM to think the engine is hot when it is not. If it does this within say a minute of being started or even setting still and just turning on the key I would check the ECT first.