Performed heating maintenance on one heat pump system. Checked electrical, mechanical and performance of the system. I found that the UV lights had tripped the transformer and were not working. I added another transformer (covered under Garner A/C warranty) and moved one of the lights to the new transformer. Cycled power and now all three lights are on at this time. I also found that the defrost board timer was set to 90 minutes, so I lowered it to 60 minutes to prevent the condenser coil from freezing. No other major issues were found. System is on at this time.