a/c compressor knock

[57 3100]

guys,
i have a 1990 k-1500 4x4 with 5.7 engine. a/c compressor about 18 months old. i hear a slight knock in the compressor when running the a/c. last night it seemed to get a little louder.
is there a way to add oil to freon and have someone "top it off" with the freon/oil mixture, or can you only add oil before adding the freon ?
thanks much.
leonard

[scotts62]

Best to vacuum the system and inject the oil then the freon. If it is making noise then its probably too late and is putting debris through the system.

[57 3100]

Originally Posted by scotts62

Best to vacuum the system and inject the oil then the freon. If it is making noise then its probably too late and is putting debris through the system.

thanks scott.. yea, im getting all new comp, accumulator, orifice screen and recharge next week. like you said, i have found out that once its knocking its too late.
by the way, nice fab work on your 62.. way cool truck man.
leonard

[scotts62]

Cool hope you get it all fixed up.

Thanks appreciate it