Overheating?

Hello, have you checked the fan clutch on the truck? If you grab the fan and turn it, you should feel a slight resistance but still be able to turn it. If you feel no resistance, then it is worn out. Let's start there.

If the truck has been sitting for so long, I would check to see if there is an abundance of leaves, dirt, animal bedding (mice, birds, etc.) that would be blocking airflow through the radiator & condenser. A good blast with the hose pipe should do the trick.

Please let me know,
William