Air conditioner noise on 2000 Dodge Durango

Last summer the air conditioner began to make a noise...something between a goose honking and a roar...only happens intermittantly, not a constant noise. The air is working fine. The problem seems to worsen when we turn it on high. Any idea what is causing the noise?

1 answer
my mechanic seemed to feel it was the drivers side condenser motor fan which I had replaced today. Still making the noise. I got a brand new compressor as well. Not happy.