Hello, I have an '04 TB with about 240 k on it. Lately I have a strange growling noise from what seems to be the front of the engine. Only occurs when engine is cold and stops usually after truck has shifted into 2nd gear. Can be heard occasionally when truck is warm though. I am thinking it could be the fan clutch or a.c. compressor clutch. A.c. is still cooling fine and it isn't making any whining noise. Any thoughts?