'07 A/C makes a intermittent groaning/howling noise

[SAAC MK1]

Now that spring is here and I've started using the A/C again it has started to make an intermittent groaning or howling noise that lasts about 5 to 10 seconds. Any ideas on where to start?

 

[digifoss]

It may do that if you have too much freon in the system. It could be other things as well. I would have it checked out.