I live in a colonial style house with 3 bedrooms on the second floor. Cool air flows through the registers in the master bedroom while the heat supply to the other 2 smaller bedrooms seems OK, though could be better. I have closed some of the registers on the first floor but this has not rectified the problem. Any suggestions about what to do next? Thanks.

You need to find the restriction in the line going to the upstairs. Is this a heat pump system? Is your furnace filter clean? How much force is behind the air movement?

Thanks for the quick reply. I have a gas furnace that is only 4 yrs old and the filter was recently changed. The force of the air is moderate in the bedrooms, stronger on the first floor. Where would I find the restriction in the line going upstairs? Don't know a lot about heating systems.

You could look for a damper handle on the supply to the upstairs. You might also check into a higher blower motor speed.

You might need to have a HVAC company out to take a look at your system also.

Ok, will do. Thanks so much for your help.