Frainer entered the Order of Friars Minor Capuchin and was ordained a priest by the Archbishop of Porto Alegre, Alfredo Vicente Scherer, on March 27, 1955. Pope Paul VI appointed Frainer on January 3, 1978 the first prelate of the territorial prelature of Coxim, which was established on the same date. The apostolic nuncio in Brazil, Archbishop Carmine Rocco, consecrated Frainer as a bishop on April 9 of the same year; Co-consecrators were Benedito Zorzi, Bishop of Caxias do Sul, and Antônio Barbosa SDB, bishop of Campo Grande. Frainer's motto as a bishop was Evangelisare misit me ("He sent me to evangelize").
On January 5, 1985, Frainer was appointed archbishop of Archdiocese of Manaus by Pope John Paul II and on May 22, 1991, Frainer was appointed archbishop of Archdiocese of Juiz de Fora. On November 28, 2001, John Paul II accepted his resignation for health reasons.
