The airconditioning unit is displaying an err 79, what does this mean then suddenly the unit stops running, what is the problem?

The airconditioning unit is displaying an err 79, what does this mean then suddenly the unit stops running, what is the problem?


I`ve never seen a aircondition that display`s anything, let alone an err79.
What is brand and model number of the ac?

Or are you talking about a thermostat? Either one, more info would be needed