AC air intake.

[kentterry]

I have an older home with a 13 year old unit. The air doesn't blow very hard out of the registers. The air intake in the hall is 20x20 and seems small to me. Will enlarging the size of the intake increase the airflow from the registers? Will this be bad for the unit? Please help.

[beenthere]

Not enough info.

Increasing just the grille itself may not be enough, the return duct may also be too small.

You need a contractor to evaluate the entire system.

[amickracing]

What he said.

But also be sure to check the filter. Once they start getting clogged up it'll really screw up the air flow. Or if it's been allowed to get too dirty or run with out one the coil might be plugged up too.

Lots of variables to that problem, but nothing a professional can't fix ;-)

[PullaVac]

I was taugh that your return sizing needs to be 20% bigger minimum than the total supply. This has always worked well for me. I have seen plenty return air grilles that were sized correct, but to find that the ducting on the other side was way to small. Dirty filter, dirty evaporator, with blower blades laden with dirt to add drag on the motor, and run caps that are on their last leg ( below there correct sized value) also contribute to less air intake.