Chrysler Repair: Roaring noise, concorde lxi, noise question

Question
QUESTION: Hi Russell,

I own a '98 Concorde LXI. When I accelerate after -let's say a stop at a traffic light- and have the heater or the a/c on, I can hear a loud roaring noise. This noise only goes away when I turn off the heater or a/c. Could this be the blower?

Thanks in advance and best regards,
Mike

ANSWER: Possibly. Is the noise coming from inside the cabin or the engine compartment?

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QUESTION: It comes from the engine compartment and it is variable. It sounds like a fan that gets too much power. And it gets louder when accelerating while driving as well, then it turns quiet again for a bit until acceleration.

Thanks a bunch,
Mike

Answer
I must start off by stating that diagnosing noise complaints on-line is tricky at best. There is nothing that the two modes of HVAC, A/C and heater, operation share in common that would generate the noise you describe. With the exception of the heater control being set to Defrost. In which case the the A/C compressor would be engaged at times in order to remove excess moisture from the air. If you are sure that the noise goes away when the HVAC control is set to OFF then I would suspect that that A/C compressor or the high speed radiator fan is failing. I would recommend that you have someone actually listen to the noise who is knowledgeable in auto repair before you start replacing suspected parts.