Be afraid. Be very afraid.
While we were on vacation in July, the AC stopped blowing cold ait at our townhouse (rental property). We called Hammocks (they had done some minor work for us in the past) and they told us it would be $1200 to repair, acid wash the units, etc. We really couldn't get a second opinion because we were out of town and it was July, and we couldn't leave our renter without AC, so we paid for the repairs.
Flash to last week, when they called me soliciting a $69 service call to check out the furnace units for the winter, change the filters, etc. I made an appointment and I received a call from them on the following Saturday when they were at the property. They told me that the furnace was cracked, woe unto us, but for $1200 they could repair it. And also, that they didn't change the filters and the service call charge was $99 (which I told the service tech I would not pay). I called Bartlett's for a second opinion, and lo and behold, the furnace is hunky-dory, and the only way it could crack, according to their tech, is if someone went at it with a blowtorch, as it is a stainless drum configuration.
Moral of the story? Stay away from Hammocks.