I have a new variable speed kenmore furnace installed two months before. When heating system is on furnace operates very quitely. Now I switched on A/C and sound of air flow at "return air plenum" is horribly high. Does A/C system makes more noice than heating system??

Thanks,
Vasu.

The fan in A/C runs on a higher speed than in heating. Since this is newly installed, I would call the installer back and discuss with them. They will be able to quiet noise down