The temperature that is too hot for an air conditioner is a temperature of above 100 F.
Air conditioners are designed to work and function when temperatures outside are 100 F degrees or less.
The air conditioner will still work at above 100 F but it will not cool a home or room as good and will have to work harder to cool the room and will usually run nonstop.
In temperatures of 100 F or above you will usually require more than one air conditioner to cool even a room.
My central air conditioner in my home works okay when the temperature outside is 100 F but if the temperature outside gets above 100 F then I need to have my central air conditioner on and also a few window air conditioners on to keep the home and rooms cool.
Once the temperature is below 100 F then the central air conditioner keeps the house cool enough.
As long as your air conditioner is properly sized for the home or room it should keep keep the home cool enough at temperatures up to 100 F.
Also if you don't have enough insulation or have leaky windows, doors etc then the cool air won't stay in the house or room and will also cause the air conditioner to take longer to cool the room and cause it to work harder which also increases wear and tear on the air conditioner and increases your electric bill.
Insulating your home properly and sealing doors and windows and other crevices and holes such as around pipes etc in your home can help to keep the cool air in and keep your air conditioner from working as hard.
When outside temperatures are pushing 100 F degrees, try setting your thermostat at 78-80 degrees.
Supplement the indoor airflow with fans and other strategies to maintain cool temperatures inside.
Your AC has limits, no matter its age, how well it was installed, its manufacturer, etc.
As a rule of thumb, when it's 95 F out, your AC can cool your house to approximately 70 F-80 F.
Your air conditioner will be able to cool to about 15 F-25 F degrees from the outside temperature.
On days that are warm, but not unbearably hot, your AC should run less.
In warm weather, your AC cycle should run every 15 minutes or so.
When temperatures outside become higher than 100 degrees Fahrenheit, the air conditioning system can consume more energy and begin to malfunction or fail.
Most air conditioning systems are designed to function with outside temperatures of 100 degrees or less.