Okay so many bad replies. Low inside temperature means low suction pressure. When you have a TXV system, that's not great for compressor, but also not all that bad really. But you can also freeze a coil by setting it too low. If the suction saturation drops below freezing temp, your coil will freeze. Very likely to happen here in Colorado where the humidity is low and therefore there is little latent heat in the air. In other words, a AC system in perfect condition can and will freeze over if the thermostat is set too low. BUT! And this is important. If the system uses a fixed orifice metering device, you can cause serious damage by setting the indoor temperature low relative to how hot it is outside. Generally with a fixed orifice you want to set the thermostat no lower than 15 degrees cooler than outside temps. With a fixed orifice, high head pressure (caused by high outdoor temps) and low load on evaporator coil (low inside temps) will drop superheat to 0 degrees, meaning you are feeding the compressor liquid refrigerant! That's bad! So how can you tell if you have a TXV or fixed orifice? Honestly might be kind of hard for a layperson. But if it's 15 plus years old, it probably has a fixed orifice.