I have a very old Trane heat pump - split system. The manufacturing date says 1984. Up until the last year it has been extraordinarily reliable. During one of the hottest summers on record in Central Florida it seemed to be struggling. I had a local AC tech come and take a look at it. He said it was fine except it might be a little low on freon. He topped it off and it appeared to work fine. A few weeks later I noticed the unit was running but it wasn't blowing cold air. I shut the whole system down with the thermostat and breakers and retried it about 10 minutes later - no luck. Called the same tech, he came out the next day and the unit restarted and ran perfectly - @#%&. He said he took a small amount of freon out of the system - hmm, sounded suspiciously like he may have overfilled it the time before.
This winter the unit has worked well again until the last week or so. We've had some very cold weather for Central Florida and it has begun doing the same thing but in the heating cycle. It starts out blowing heated air, but after about 10 minutes it stops heating the air but continues to run. If I shut the whole system down, wait a considerable amount of time and restart, it works for a awhile again. To little-old-ignorant me it sounds like too much or too little freon, or a pressure switch is shutting off the compressor.
What do you think?