im getting 3sec interval knocking noise coming from the general area of the ac compressor. Almost sounds like a rod knock but only happens with the ac on. Is this related to the issues of people having noisy compressors that need to be replaced or maybe low charge not having enough oil to lub the internals of the compressor. any suggestions?

 

How is the AC performing? Blowing cold? Maybe it could be the clutch in the compressor or maybe even the shaft.. Good luck... Keep us posted...

 

ac blows cold real cold in fact

 

mine does same exact thing. just started happening today. scared the ish outa me cause im twin turbod, thankfully its just the ac fan. Sometimes things from the glove box fall in there and make it make a funny noise so check that out. also the bolt on the fan might just be loose.