When my wife was in the HVAC biz she got one of these calls. She found the planted bug pretty quick (a jammed float switch in the condensate pan that shuts off the compressor), she didn't try to sell anything or even charge for the call and the whole clip ended on the cutting room floor.
It was really a pretty raw deal because they made the call sound like they wanted to see a salesman. Most HVAC "techs" are on commission. Whether someone should replace a 10SEER or older machine with something newer and more efficient is certainly more of a judgement call than simply what is wrong with it when the tech shows up. Throwing away a perfectly good 20 year old machine for a new one paid for itself in about 4 years, just in electric bills and I got an FPL rebate that pushed that payback period up a year. It is rude not to fix the easy problem simply to make a sale tho.
