Nissan,My heat and air turns on without a problem but does not blow very hard (heat blows harder than air). Rattling noise.

Will be taking in for a diagnosis and estimate but curious as what to expect…The heat and air turns on without a problem but it does not blow very hard. It's been declining over the past several weeks. A rattling noise just started this weekend. The heat will eventually begin blowing very hard (normally), but the air struggles. Temperature is cold or hot accordingly, but cold is without the power of a "blower,' and the heat "blower" is slow to kick into gear. Thank you.

My car has 53000 miles.
My car has an automatic transmission.