Greenhouse air conditioners, like all mechanical systems, can encounter issues. For instance, a noticeable decrease in efficiency might indicate a refrigerant leak or dirty filters. If the system cannot maintain stable temperatures, it might be due to faulty thermostats or sensor problems. When the AC struggles to reach set temperatures, the system might be undersized for the greenhouse or have a blocked condenser unit. Humidity control issues often stem from problems with the dehumidification system or malfunctioning sensors. Regular maintenance, understanding the nuances of your specific AC model, and occasionally seeking professional help are the best ways to ensure such problems are effectively addressed.