Responded to a no-cooling request from a commercial customer in Tracy California. Our local HVAC technician arrived and troubleshooted RTU #5, finding the belt had broken and the VFD had failed. Replaced the belt and bypassed the VFD to bring the unit up and running, until the VFD can be replaced. Also inspected Lennox unit #4 and found it tripped on high head pressure for circuit #2. Condenser fan motor had failed on that circuit. Disconnected the circuit, leaving unit running on one stage for cooling. Will quote and order necessary parts for repairs.