Auto Parts: 2000 Caravan A/C noise, freon gas, clutch assembly

Question
Hi,
After replacing a leaking A/C condenser and  filling  the A/C unit  Freon gas, the A/C  does a good job of cooling. However, every time the compressor kicks in or out, a loud shrieking noise for a second or less is heard.
Do you have any ideas of why?
Thanks,
Tibby


Answer
    When the clutch on the compressor engages, it momentarily puts a rather high load on the clutch/hub/pulley.  If the the adjustment of the air-gap between the hub and the clutch face is close to its outer limit (or beyond) the engagement will be drawn out and it will squeal as the surfaces slip against each other before clamping together securely.  It is also possible, though less likely, that the electromagnet that clamps the two parts together is going south and needs replacing (you would generally replace the whole clutch assembly in that case).  Lastly, and most likely, the belt is slipping on the pulley.  If you have a 3.0, then there is a separate V-belt that drives the A/C compressor and they are very prone to glazing on both the pulley and the belt.  Best bet there is to change the belt, make sure that it is properly tensioned, and rough up the groove in the pulley with a little 220 sandpaper to make sure the new belt gets a good bite.  If you have a 3.3, then everything drives off of one serpentine belt, and it should be replaced along with the tensioner.