I had read all reviews on Black Mtn. Air,almost all positive, before I called them when my air condition stopped blowing cold,I turned the system off ,they came and checked the unit outside, couldn't find anything wrong,we turned it back on and it blew cold.Go figure? He said call back if the problem occurs again,no second charge for the service call,fair enough.It did 1 week later,he came and did the same thing,only this time he  charged the system which made no difference!.Then he went in the attic and said it must be a problem with the TXV valve but the part was not on his truck anyway,he said he had to ask someone with more experience to make sure?He said he was sorry and would call me in the morning. Why? They advertise 24 hr service,and shouldn't they have many popular parts in stock at their shop, or at least have a good supply network? He never called next morning,when I called,I was told by the secretary that they couldn't figure what was wrong and would refund my service fee,but how can you run a company and leave someone in 100 degree heat? It is like taking your car to a mechanic, and he says I cant figure out what is wrong with your car,you can come pick it up now.Very dissappointed.