I have a 2002 Honda Accord EX 3.0L V6
Ive noticed a weird fizzling kind of noise coming from the passenger side behind the air vent. It kinda sounds like someone trying to slurp the last of their drink through a straw. Over the summer it would come and go, I mostly noticed it when the a/c was running. Now I hear it almost all the time. My heat and a/c both work well. It sounds like maybe a fan could be hitting something? I replaced the cabin air filter not long ago, and I'm pretty sure I had the noise before that but I'm not entirely positive. Any ideas?

 

Coolant. When was your last coolant change? Could still have air pockets. That was my issue.

 

Ive never had it changed... Its been pretty full the whole time ive had the car (since maybe April this year) air pockets sounds pretty likely. What can I do about that?

 

I did a fluid change and replace my air mix motor. I think the motor was the issue

 

I'm curious, did you find out what was going on? My guess is that it was a leaking refrigerant line/valve stem. Specifically because you said it sounded like the noise was coming from the passenger side air vent near where those lines are located under the hood. Let us know!