I’m looking for some advice on a strange issue with my approximately 30-year-old central HVAC system. When I lower the thermostat by 1–2 degrees, the air conditioner will run continuously for a very long time before it finally reaches the new set temperature. For example, if I change the thermostat from 76°F to 75°F, it may eventually reach 75°F, but the AC keeps running even after the thermostat shows it has reached the set point. I’ve also noticed that the house feels much colder than the thermostat setting while it’s still running. The really confusing part is this: if I then raise the thermostat back up to 76°F, the AC immediately shuts off—even though the thermostat may now show the room temperature is 73°F. That doesn’t seem to make sense to me. Has anyone experienced something similar? What are the most likely things I should check or have inspected? Could this be a thermostat issue, a sensor problem, an airflow issue, or something else? The system is about 30 years old, but it still cools the house. I’m just trying to understand why it seems to overcool and why it won’t shut off until I manually increase the thermostat setting. Any advice or troubleshooting suggestions would be greatly appreciated. Thank you!

See picture - both lines drop water when AC is running. Any ideas on what the cause is or is this normal? Any suggestions on what do about this? Thanks