The temperature difference between the outside air and the inside air that is necessary for an air conditioner to work efficiently can vary depending on several factors, including the specific design and efficiency of the air conditioning unit, the insulation and sealing of the building, and the outdoor climate conditions. However, a general rule of thumb is that air conditioners tend to work most efficiently when the outside temperature is higher than the desired indoor temperature.
In many cases, air conditioners are designed to maintain a temperature difference of around 15 to 20 degrees Fahrenheit (8 to 11 degrees Celsius) between the indoor and outdoor temperatures. For example, if you want to maintain a comfortable indoor temperature of 72°F (22°C) during a hot summer day, the outside temperature should ideally be around 87°F to 92°F (30°C to 33°C) for the air conditioner to operate efficiently.
If the outside temperature is too close to or below the desired indoor temperature, the air conditioner's efficiency may decrease, and it may struggle to provide sufficient cooling. In extreme cases, if the outside temperature is too high, the air conditioner may also struggle to cool the air to the desired indoor temperature, leading to longer cooling cycles and potential strain on the unit.
Keep in mind that these temperature differences are general guidelines, and the efficiency of an air conditioner can be affected by various other factors, including the unit's size, SEER (Seasonal Energy Efficiency Ratio) rating, maintenance, insulation of the building, and the quality of windows and doors.
For the most accurate and efficient cooling performance, it's essential to choose an air conditioner with the right capacity for your space, maintain the unit regularly, and ensure your home is properly insulated to minimize heat gain from the outside.