Whenever the court under section 18 of this act enters a reimbursement order and the parent or other adult legally responsible for the care of the child fails or refuses to obey and perform the order, and has been found guilty of contempt of court for such failure or refusal, the court making the order may order an assignment to the county or state of the salary, wages or other income of the person responsible for the care of the child, which assignment shall continue until the support is paid in full. The order of assignment shall be effective 1 week after service upon the employer of a true copy of the order by personal service or by registered or certified mail. Thereafter the employer shall withhold from the earnings due the employee the amount specified in the order of assignment for transmittal to the county or state until notified by the court that the support arrearage is paid in full. An employer shall not use the assignment as a basis, in whole or in part, for the discharge of an employee or for any other disciplinary action against an employee. Compliance by an employer with the order of assignment operates as a discharge of the employer’s liability to the employee as to that portion of the employee’s earnings so affected.