Air conditioning compressor noise

I just finished installing a R143a conversion kit on my '93 protege. I also installed a new drier and pumped the system down for 30 minutes before refilling it. Now the system works good when I am moving (higher RPMs). The problem is when the RPMs fall below 1000 the compressor makes a loud clicking sound. I don’t want to buy another compressor unless I have to, but I am worried about a failure that would introduce debris into the system/lines. ??? any help/advice is appreciated ???

you must know something to do a ac vacuum and filling system Does the clutch jump off and on? low gasin system. or clutch is bad. you might have a bad pressure switch telling system is low. you did add a/c oil into system. too much oil is bad. and causes problems. good luck it hot these days

Sounds like a lack of airflow causing the compressor to click off on overload or the high pressure switch to open. Could also be an internal relief valve.
What are the pressures?