I have a AVPTC31371 indoor in the attic of my 2 story house connected to a asx140241 outdoor heatpump condensor. When the temp drops below approx 32 degrees the unit groans and vibrates the house for the first 5 to 10 seconds when it starts. It then quiets down and runs normal. Doesn't seem to do it when the temp is 35 degrees and higher.

I have anther duplicated set on the first floor and both of these were installed in October. The first floor unit is quiet even on start up.

I am lost and need some advice. The company that installed the system says this is normal.

It wakes everyone up at night when it comes on....this cannot be "normal"

Any help would be greatly appreciated.