The proceeds from the sale of such bonds and notes, except refunding bonds and notes, shall be deposited in a fund designated “the Housing Mortgage Fund”, which fund shall be used to make the loans authorized by this part. Payments from the fund shall be made by the State Treasurer on certification of the Commissioner of Housing. All repayments of interest and principal on loans by the state, as authorized by this part, shall be paid to the State Treasurer for deposit in said fund. The principal of, and interest on, such bonds and notes, not paid from refunding bonds and notes, shall be paid first out of the moneys in said fund and, if in any year said fund is not sufficient, then such deficit shall be paid from the General Fund of the state; and, if in any year said fund is more than sufficient to meet the principal of such bonds and notes maturing in such year and the interest thereon, the excess shall be used to reimburse the state for any such deficit and the balance thereof shall be applied to the payment of, and principal on, the bonds and notes maturing in any succeeding year or years.