I was just giving a possibility. Not an answer. But that "Ants" thread was very amusing. "Marge" had some issues admitting she was wrong. Got to love being at "their" homes. They are the ones who makes us earn our paycheck!
I would agree to have your tech suspect both the outdoor fan motor or capacitor as well as the thermostat.
You can actually be a big help with this one by noting the next time the cooling stops and the outdoor fan is not running to check the large refrigerant tubing that is covered with black rubber insulation to see if it is cold. If the outdoor unit is not operating and that large copper tubing is very cold, it is more then likely that either the outdoor fan motor of the capacitor is periodically failing. If this is the case, I would recommend replacing both the motor and the capacitor no matter which is determined to be at fault. Especially having been operating under such adverse conditions, either one failed would have severely damaged the other.
As for the Maple Chase thermostat, I have also found them to be more bothersome then they are worth. Erratic operations are usually the complaints. Maple Chase and Hunter thermostats seem to be the most troublesome of the consumer readily available thermostats. Lux thermostats used to be almost as bad a few years back, but Lux has done a wonderful job in making their thermostats much more reliable now.
I thought I would provide an update since there has been such a generous community response. My AC man came by this morning and I shared your comments - he was very impressed that I took the time to investigate matters on my own He encouraged me to continue the discussion online and get your inputs into what he did next. He did not know that this online discussion group existed - I hope I did not embarass him
He removed the cover panels off of each outside AC unit. The larger unit (the one that is working intermittently) has a small circuit thingy near the 'relay'. The smaller outside AC unit does not have this circuit, even though they are the same brand and age, the smaller one simply did not have one!
He disconnected the circuit from the intermittent AC unit and reconnected the remaining wires the same way as the smaller unit. My AC man then turned on the intermittent AC unit and it started and has been running perfect since this morning!
He thinks the problem is that the circuit is bad and new one needs to be installed to be certain. He said to keep the unit running until he returns later today to install a new circuit because he says it does serve a purpose.
He agreed with you all about the thermostat and said he will replace them when he returns later today. My AC man also thinks there may be other problems that may yet need his attention, but for now, he will take it one step at a time.
I told him the ant story and he was rather amused.
PS This is rather like a detective story - what fun!