stupid nubee question regarding noisy compressor

Hi all,
I've got a Amana Ultra Prestige compressor (?) (the thing outside, with the big fan, motor, coils and what sounds like a pump). Forgive me I just moved to Central TX from New Mexico where we are blessed to only need evaporative coolers.
Anyway, the thing outside is seems to be getting noisier. It's making a rapid pumping noise around 180 to 240 bpm. Probably the sound of the pump. I looked inside and all I saw was the big fan and what looks like a pump wrapped up in a insulated blanket. Is there something I should do? Should I just live with the noise and is this normal for an Amana to be on the noisy side? My house is under warranty and I'm not sure this would be covered because the a/c seems to be working fine.
In relationship to the other compressors in my neighborhood this one seems larger compared to other similar size homes. My neighbor has the same size house with a much smaller compressor.
Oh yeah, another thing. I have an attic fan I just recently replaced. Do these things actually help cut the cost of operating the a/c?
Thanks in advance and hopefully these questions don't sound too idiotic.
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