Our 3 year-old geothermal 1-ton attic system occasionally shuts off. Each time it does, we're given a different reason for the shutdown. The most recent shutdown was caused, we were told, by low refrigerant levels - they said we needed 2 pounds added. Incidentally, we noticed our most recent maintenance agreement was changed from the prior two agreements to omit, you guessed it, 2 pounds of refrigerant added if needed. So we had to pay for the refrigerant.
Now I'm wondering what comes next. If we need refrigerant there must be a leak, right? Or does it somehow evaporate in the system over time? Our geothermal system is still under warranty. I want to approach the business that installed the system but thought I could use more information beforehand. Any thoughts on this? Is it common? Is this toxic?