I have a Ram 1500 5.7l hemi with approximately 140k miles. The A/C stopped blowing cold air. I was told by a mechanic friend of mine that if my a/c system does not have any/enough refrigerant in it then the compressor clutch will not engage. (which it doesn't) Would it be worth the $39.99 to by the a/c recharge kit from an Auto Zone, or O'Reilly's? Or should I take a different approach. I do not want to take my truck in anywhere to have it worked on, I enjoy working on my own Truck.