I'm hoping someone may be able to help to advise if my geothermal unit can be damaged by frozen loops, and how to evaluate if it is ok. I had a horizontally-drilled closed-loop geothermal system installed about 2 years ago. We had a less-than-smooth process with our installer, and have recently had a freeze problem with the ground loops. We live in Northern California, so temps are not as cold as other areas. However, we had a colder-than-normal 3 weeks where night-time temps went down to about 25-28, and our geo system started blowing cold air intermittantly. The installer finally came out, but the first 3-4 visits, the system had unfrozen (his visits were in the late afternoons). He finally came on a cold morning, and found that the loops were frozen, as they had not put in anti-freeze/alcohol (it was their first horizontal job vs vertical drilling). They added alcohol, and it works ok, but now turns on very hard and loud. The system froze and unfroze on-and-off for about 3 weeks, with probably about 8 or 9 times it froze. How bad can this be for the unit presently, as well as for long-term/future functioning and life-expectancy? thanks!