Faulty high pressure switch, recommend replacement. Tech returned and recovered refrigerant. Tech removed old high pressure switch and began brazing in new high pressure switch, while tech was brazing torch got stuck and burnt new high pressure switch. Tech had to reinstall failed pressure switch to get system back heating at this time. Will need to order new high pressure switch and return to replace. Tech did go ahead and completed maintenance on system per customer request. Will need two 20x25x1 filters when we return to repair.