Originally Posted by hvacgaspiping
You say your house is kept at 67 degrees? Your A/C compressor is on the brink of failure at those temps, as the refrigerant coming back into it is cold enough to be turning back into liquid droplets. This is what causes mechanical failures inside a compressor. They really need to turn it up to 70 to stand a better chance of avoiding this type of problem.
Umm, I would have to disagree with that statement. Considering the average home A/C unit uses R-22, which boils at -40 C at atmospheric pressure, and corrolate that to average suction pressure of 63psig, which if you would fallow the pressure/temperature relationship of R-22, the temp at which it would boil goes up. Then you would have to factor in the Superheat. Just like using R-22 as a commercial cooler refrigerant, you dont need a defrost timer.
As a matter of fact, you could pass 0 C air over an evaporator and still have enough heat transfer to boil all the refrigerant. The only problem with that would be keeping the water vapor from sublimation, as refrigerant absorbs that much "latent" heat, which is the pure basis of an air conditioning system.
My point is, it doesnt matter if your thermostat is set to 50, as long as the unit is not overcharged, freezing up, or filter/coil is clogged/dirty and the system 4 components are operating at standard, there will be fractional to no liquid going back to the compressor.