Well, the "clicking" has stopped; outside temp reached 35 degrees; strange; the sound was coming from the upper left corner of the case ,directly behind the on,off switch. I suspect a relay with "contacts" problems; too cold to open and repair.

I had a furnace that did that constantly--because of an improper installation, it wasn't getting enough air flow and its 'high limit" switch kept shutting down to prevent the furnace from getting too hot. Has it always done this? If it's a recent thing, it may because you've blocked off some ducts. In any event, it should be checked.

High limit switches are usually very reliable. Dollars to donuts the furnace is overheating and shutting off for a reason. That's not unusual when furnaces run for lengthy periods of time in cold weather, since that lengthy run gives the furnace time to overheat. The usual cause of that is reduced airflow through the furnace, caused by a dirty air filter, covered up air return grate, too many warm air vents closed, fan speed set too low, overfired furnace, duct work undersized or other causes. Usually such problems are pretty easy to diagnose and correct --- the problem is diagnosed by putting a thermometer in the warm air ductwork coming from the furnace and vrifying that the furnace shuts off at the temperature specified by the limit switch (which is calibrated in degrees). Replacing all those parts was probably a waste. You need to verify that the limit switch is opening because the furnace is overheating and then determine the cause of that problem.

Sure, and the ball on the half yard line is not a Touch Down. 'Comfort means different things, to different people... and because neither of you have a communicating system doesn't mean I can explain fully in text what that means.' But if you were comparing a Trane 2 speed non-communicating (legacy) system to a Goodman / Amana 2 speed communicating system and the price was similar for either one... which one would you choose? That is what changes the dynamics of the equation --- does it not? BUT, you have to know which is actually the better of the two and why. #Ah that old devil in the details again! On a side note: Have either one of you dealt with a customer who was a 'hot box'? Someone that is highly sensitive to heat? Not everyone deals with these issues... especially men. Women are known to suffer from what are called 'hot flashes'. And so because you don't realize this you are going to cut yourself off from 50% more business to actually solving a big problem? Yeah more unadulterated non-sense from me. Pay no attention to it.