[Richard]

Let's make sure you understand what you are looking for on the fan situation. As you look into the engine bay, focus on the compartment to the left of the engine where the fan motor is located. The fan speed control box will be mounted on an upright support just to the left of the engine, and at the bottom of the support. There will be a couple of hydraulic hoses connected to the box. One goes to the fan motor obviously. That box controls the fan speed. There are only two speeds high and low. The default speed is high. So, if the electrical connection to the box is unplugged or wasn't plugged back together the fan will run on high. If the solenoid valve in the control box fails, the fan will run on high all the time. There is no sensor, per se. I believe the signal to that box comes from the DDEC computer.

Look carefully at Tom's post above, on the top side of the fan motor is a fitting that is very hard to tighten correctly. I would check there first before tearing into the motor and OHLA. Take a white paper towel and zip tie it around that fitting. Red ATF will show if it is leaking.