Hi grannyring,
I remember an episode of "This Old House" on PBS where they did a feature of a startup business. The business was about a system that kept track of what was happening with all the breakers in electrical panel in a home. Each conductor on each breaker had a current transformer (CT) on it. The CT's sent current draw info to a computer which had a program that recorded what was happening and kept a log that could be reviewed many months later. You could see when a motor was energized and how much the surge current was along with how long it lasted. By having a history of every breaker you could tell when things were running normally and when things started malfunctioning. They said that when things start having problems it may be long time afterwards before it becomes noticeable. That could be anything such as a hot water heating element or washing machine malfunctioning. That being said my guess would be your problem could very well be your hvac unit. If it turns on and there's much not much going on electrically in the household then it may not be enough to trip out you equipment. It could also be that something else is malfunctioning and the hvac coming on is enough to trip the conditioner. That would explain the intermittent problem. You mentioned that everything worked fine for a year so something has changed. I think we all could use one of those monitoring systems. Hope this helps.
Frank
I remember an episode of "This Old House" on PBS where they did a feature of a startup business. The business was about a system that kept track of what was happening with all the breakers in electrical panel in a home. Each conductor on each breaker had a current transformer (CT) on it. The CT's sent current draw info to a computer which had a program that recorded what was happening and kept a log that could be reviewed many months later. You could see when a motor was energized and how much the surge current was along with how long it lasted. By having a history of every breaker you could tell when things were running normally and when things started malfunctioning. They said that when things start having problems it may be long time afterwards before it becomes noticeable. That could be anything such as a hot water heating element or washing machine malfunctioning. That being said my guess would be your problem could very well be your hvac unit. If it turns on and there's much not much going on electrically in the household then it may not be enough to trip out you equipment. It could also be that something else is malfunctioning and the hvac coming on is enough to trip the conditioner. That would explain the intermittent problem. You mentioned that everything worked fine for a year so something has changed. I think we all could use one of those monitoring systems. Hope this helps.
Frank