"There Is Nothing Wrong With Your Rolls-Royce"

      So, the tech arrived, checked out our air-conditioning, and--

      And announced there was nothing wrong with it.  How cold had we set the thermostat?  75 degrees, really.  Well, you can't expect to be any more than 20 degrees cooler than the outside air in a house this old and so thinly insulated.  And a new filter?  He took a look at it--

      Whoops.  1500?  You really shouldn't use anything above 750.  The higher ratings do more harm by restricting air than they do good in catching dust.  And restricted airflow--

      I knew what that does: it makes it more likely the coil will freeze up.  We'd hit the exact wrong circumstances, record heat and a too-tight filter.  There's plenty of working fluid, the compressor coils outside are clean and the system is working -- if I will only keep out of its way.

      Bonus, we have to buy cheaper filters.