Bickering over the A/C temperature setting in one’s home has been going on for five or six decades; around the time that air-conditioning became common in houses. The thermostat that controls that A/C unit can trace its origin back 400 years or so. The issue at hand: One partner wants the setting to be 69 degrees, and the other partner wants it set at 72 degrees. The good news here is that this discussion (fighting, bickering, arguing) is usually over only a few degrees one way or the other a few times a day, and in most cases does not cause additional wear and tear on the A/C unit. However, big reductions in a thermostat’s temperature settings (like setting the temperature to something less than 69 degrees) can and usually does cause issues and it is not needed or necessary.
Whether we look back six decades or 40 decades some people do not have the foggiest idea of how a thermostat works. In short, a thermostat in your house, RV, refrigerator, freezer, water-heater etc. work the same way. The ambient temperate at the probe drops to or rises to a preset temperature…a loop is closed causing the compressor or heat strip to activate. Once the ambient temperature reaches the preset setting (within a degree or two) the loop is opened, and the compressor or heat strip cuts off. Very simple right?
How am I so sure that some people are clueless about this subject? One example is your car. How many times have you set your car’s temperature to 72 degrees in the summer and then you let a valet bring your car around and when you get in your car you find the A/C is set to the minimum temperature? If the inside of your car is 110 degrees and the A/C is set at 72 degrees, the compressor will engage once the engine is started. Why did the valet turn the A/C to its lowest setting….because the valet does not understand how a thermostat works and believes that setting the temperature to a lower setting makes the air blow colder. At least this act does not hurt your car….but because of this act, the same valet likely does do harm in other instances. I will offer a few more examples below….but first, a quick review about how most thermostats work on A/C units you may come across.
Most modern household thermostats are of a digital design and have one number displayed which is the “setting” you wish the ambient temperature in the room to be….and another number which is the “current” ambient temperature around the thermostat. Most then show which mode the unit is set to. I.E. Heat or Cool. And if the unit is set to “COOL” for example, the word "cool" will flash or display “cooling on” when the compressor is engaged (i.e. the loop is closed).
Some window A/C units, refrigerators, and some units in RV’s have numbers on a dial vs. a temperature setting. That makes no difference except that many times (in older units) the "max cold" setting on the dial will engage the compressor (close the loop) and not allow it to disengage no matter how low the ambient temperature around the probe.
The main thing to understand is that when a compressor is engaged it is engaged. So, if it is say 90 degrees outside, your A/C unit is set on 73 degrees in your house, or on the number 4 in your RV, and the compressor is engaged; turning the thermostat down to 65 or to max cold (in your RV) will not have any effect on the temperature of the air blowing out of the vents.
Why is all this important to you. Well, take for instance at you and your RV; as complaints about RV air-conditioning units not working properly during the summer are a common one. Assume you have the A/C unit set at 4 and you are very comfortable until the West sun hits your RV on a 110-degree summer afternoon. You decide to turn the unit down to “1” or “max cold” and you go to bed. During the night the ambient temperature outside drops to around 75 degrees and your A/C is turned down to a point where it would have to get below 50 degrees inside your RV to disengage or perhaps may never disengage due to being set on “max cold”. And let’s assume the humidity is high and your condenser and/or evaporation coils are dirty; or your filter needs changed; or the freon is slightly low. There is a very high probability your unit will freeze up. Once the coils are frozen-up; air is no longer blowing across the coils and your RV begins to heat up but you don’t realize this till sometime the next day. All those hours your A/C unit is operating in a frozen-up condition is just increasing your electric bill and decreasing the life of your A/C unit. All this is costing you MONEY!
Another common issue we see is with a thermostat at a business. In this example assume a customer is at restaurant and they decide it is hot at their table; and instead of asking the manager to see if he/she can adjust the temperature a few degrees….they decide to adjust it themselves. They locate the thermostat and find the unit is blowing air, the setting is 72 degrees and the ambient temperature (the one showing on the thermostat) is 78 degrees and the COOL sign is flashing. What could this mean. Well, just what it is showing. The unit is on…the compressor is engaged….and the room is not at 72 degrees, it is much hotter. Why? Maybe the door(s) have been opened a lot, maybe it’s 110 degrees outside and the unit is undersized, maybe the unit is low on freon, or maybe another unit in the restaurant is not on or not working. But…because the customer does not understand how a thermostat works, they decide to turn the setting down to 65 degrees, thinking that it will make the unit blow colder air. Well, later that evening there is a good chance that the manager of the restaurant (who did not know someone adjusted the temperature on the thermostat) will lock up and leave. Later that night the unit will likely freeze up and it will likely not be discovered until later the next day. Then the unit will have to be turned off for several hours to thaw out. The next afternoon the patrons will be upset, as they have to contend with 90 degree temperatures vs. the 78 degrees the day before. The electric bill of the restaurant will increase and eventually prices must increase because the electric bill and/or A/C repair bills gets out of hand.
The bottom line is this. If it is your house or RV; then clown around with the temperature on your thermostat all you want. You will eventually learn the hard way about how the thermostat effects your electric bill and repair bills.
If it is someone else’s thermostat leave it alone. PLEASE! Personally, I wish the manufacturers of thermostats would make the settings 69 to 79 degrees. It would save lots of electricity and reduce the cost of owning a business and those cost reductions could then be passed on to the consumer.
