A properly sized unit (approximately 1 ton per 400 square foot of living area or newer tighter built home about 500 square feet per ton) and a properly operating unit should easily cool a space down to 74-75 still allowing for cycling or off time. your utility bill may also help in your decision of what a comfortable setting would be.
outside temps above 100 degrees
He had to replace the thermostat in his pickup truck. Another good sentence would be, the thermostat has settings on it to kick the heat or air on, depending on the temperature outside.
On most cars the outside air temp sensor is located on the radiator support , behind the grille.
Nearest to the thermostat.
Sounds Like The Outside Thermostat Has Went Bad Try Replacing it .....
The thermostat should have a air bleed valve built in and the air bleed valve should be facing straight up.
Depends on the outdoor temp. If it's 75 outside, your system should easily bring your house down to the 68 degree setpoint. If it's 100 degrees outside, you'll never get there. Unless, that is, your system is too big for your home. Then it will cool you down just fine, but you'll have humidity problems...that's a whole other discussion. Most central air conditioning units are designed to maintain a 75 degree indoor temp at 55% relative humidity on a 95 degree day. So a indoor/outdoor temperature difference of about 20 degrees or so is what you should expect.
You should check the thermostat and the fuse for the heater.
Depending on the year, make, model along with if it has single or dual a/c systems and what the outside temperature is, it can be between 36 to 48 degrees...... Simply, the A/C vents temperature should be whatever you set the thermostat as.
but what if the ac gets frozenSure ... once the thermostat senses the cooler air, it will shut down the AC unit anyway.
thermostat probably stuck open needs to be checked or replaced
Make sure that there is no cover on the unit outside, check the AIR filter. Make sure it is clean, then go to the thermostat and turn it to cool, fan on auto and turn it down.