Heater doesn't heat one bedroom, but A/C cools it

[brax71]

We're getting settled into the new house, but are finding the quirks...  most recently, it seems that the Master Bedroom doesn't get much heat.  Strangely, it's the room that gets the most A/C by far.

House is 2-story, with a heat pump unit servicing each floor.  MBR is downstairs.  Air handler for downstairs unit is in an attic over a nearby, different downstairs bedroom.  Heated air coming out of other downstairs locations is around 89-90, but MBR heated air comes out at 68.  It really is weird b/c when it's cooling, you can hang meat in the MBR while some of the other rooms are nearly too warm for comfort.

Fortunately, we're in FLA, so the "winter" has only gotten down to 40 once or twice, but it really is both puzzling and annoying. 

Any ideas what could be going on?

[daddo]

First thing I would check is the ducting. Sounds like an open duct somewhere mixing with cold air.

In the summer, going from 90 outside to 72 inside, the difference is only 18 degrees.

In the winter, going from 40 to 72 is 32 degrees difference.