How do these kind of people stay in business? No,he is not right and I hope you didn't pay him more than $75 because that's $73 more than he's worth. Many people run thier blower 24/7 for reasons ranging from inhanced air filteration to offseting poor air distribution.
Based on his hare brained observation,I'm betting the first cap went bad as they do under normal conditions once in a blue moon. The secound time was likly because the knot head installed the wrong cap.
That's not to say caps can't go bad twice in a short time,but it's unusual,esp if everything is wired correct and there isn't a weird short circuit or such.

I would be willing to bet the capacitors contained a sub standard electrolyte which caused premature failure. Had a tv fail 1 month after warranty ran out, 4 caps , all blown. This was a major problem several years ago especially for electronic manufacturers.

How long did the first capacitor last and were you charged for the second replacement?

The capacitor failure has nothing to do with setting your thermostat at 72.

I just checked the temperature in LA. It is 44 degrees. This is considered a warm winter day for many parts of the country. Your furnace has an easy life living in LA.

Was the replacement capacitor the exact same capacitance value and equal or higher voltage rating as compared to the original 'correct' capacitor?

SR

I agree.

Either a bad bunch or wrong size/rating.

IMO