anyone experienced with ac/heater units?

[Guest guest]

I have a few questions about our new hvac unit. I think the return is

either leaking or the material used to seal it is porous. I think if

we could get this possible problem fixed it would help a lot.

There are reasons we dont want to call the people who installed it &

my husband was the one who sealed & he did a very thorough job, but i

just dont trust the material he used to be air tight, for several

reasons but he takes my saying this as a criticism on his ability to

do things right. So I was hoping someone might have experience and

give me some educated advice/opinion ...please & thnx