1989 Deville: Rattling / Vibrating Noise from Dash

I have an annoying noise coming from inside the dash when I run my A/C. It takes about 5 minutes or so after turning on the A/C for the noise to start and it's driving me nuts! It sounds like a cross between popcorn popping in a microwave and someone snoring. I have to put the fan on low for it to go away. Also, it seems like the cold air is going somewhere other than the inside of the car because I used to have a strong airflow pressure coming from the A/C vents - but now I have to close 3 out of the 4 vents in order to increase the airflow pressure. If I have all vents open it feels like the fan is on low - even though it's set to high and the fan is indeed spinning on high. I have replaced the compressor, hoses, evaporator, heater core, accumulator, and fan (blower motor). Basically it's a new system but I must be missing something. Cananyone help? Thanks.

Sven

sbernitt@yahoo.com