Why is my cooling fans running slow that both are coming on at the right time

Low and high speed fan function is controlled as needed by the engine's processor, which receives data which plays into determining what is needed. Testing is required using a diagnostic tool that can actually show what is being commanded when the concern is occurring. Also, you should be able to actively command components using a good diagnostic tool. This would assist in figuring out what the cause of the concern is. www.repairpal.com/repair-shops