On arrival, checked in with vendor log and store manager. Gained roof access. Found VFD on RTU 4 coding OH-C. Called NexRev and found that the cooling fan for VFD has failed and VFD is overheating. New VFD has been ordered and is being shipped to my home address. Will notify service managers when part has arrived. Found DrivePac board for VFD on RTU 1 has failed. Called NexRev and found that the board is not correctly controlling VFD. Ordered new board and having it shipped to my home address. Will notify service managers when part has arrived. Checked out with EMS. Filled out work order. Obtained signature on work.