Had a customer call me after their A/C units stopped working. They had a maintenance mechanic from a neighboring restaurant take over the PM on their units (cost effective). He told them their cooling problem was air in the lines of their units and that he had to bleed off the air from the units then top them off with freon. The owner got charged for 10# of 134A to replace the air in their 4 systems. Too bad they were R22 units.....