"got 2 go" wrote in message

Basically, it is up to me to prove to the builder if there is anything
wrong
with the install or not.
They sent a tech from the A/C sub they use and while he could not explain
it, he said it was probably all right.

Can anybody share their comments on this ?

You have already proved something is wrong. Air should not be coming out of
the medicine cabinet.

The tech was clueless. If your house was on fire and he could not explain
it, would he say it is probably all right?

Could be a serious leak in a duct passing in the wall, could be some serious
balance problems, could be a lack of insulation and proper sealing if on
outer walls. I may not know the correct answer, but I don know it is wrong.