There does happen to be a vacuum pump under the hood on most Class A's that operate the comfort controls. There are vacuum tubes that go to the Evans Products style comfort controls that the driver can access. Usually, that pump runs to create a vacuum as soon as you turn the key and your symptoms sound just like a dislodged or split vacuum hose after the vacuum storage canister.
So first step I'd think would be to open the hood and check for any vacuum hose that has come loose from anything under there. Or has a split. If you can't spot anything, than check RVServiceReviews
for shops in your area.