Problem: AC would not start occasionally and ice up.
I scheduled a service call, asking for an estimate (was planning to compare if with other offers). They went straight to work (I had to prompt them for an estimate as they didn't seem to be willing to cover that part first).
The diagnosis (which was the only thing included in the initial call cost) was that the freon pressure was low. That took 5 minutes. Everything else was extra. They looked for a leak, didn't really find any, they diagnosed a valve as faulty, exchanged that, topped up the freon and "cleaned" the outside unit.
Final charge: $150 over the estimation. Part of that was $50 for visual inspection and cleaning, a 2 minute job of spraying the external unit using the backyard garden hose.
When prompted about the warranty they offered for the work done, they replied they only covered the replaced part (the $2 valve). If the problem occurred again, they'd have to start from scratch and figure out where the leak was (hours of work, undoubtedly, many hundreds of dollars).
The AC kind of worked after that (although not nearly as efficiently as it used to). 2 weeks after, it stopped working altogether (wouldn't start at all). I managed to diagnose the problem using the internet forums (AC capacitor went kaput) and fixed it myself. Something they should have picked up during the service call, given the reported symptoms.
A year later, the efficiency of the AC is lame, to say the least. Very likely low on freon again (although no icing so far, and the unit starts). Guess who I won't be calling this time?