No. Lowering your thermostat from 78° to 65° will not cool your house any faster. Your air conditioner runs at the same speed regardless of the temperature you choose. Setting the thermostat much lower simply tells your AC to run longer until it reaches that temperature, which can increase energy use without cooling your home any quicker.
This is one of the most common misconceptions we hear from homeowners. At Norris Air, we’ve been helping Arizona families stay comfortable since 1973, and understanding how your thermostat actually works can help you lower energy costs, reduce wear on your air conditioner, and keep your home consistently cool during our hottest months.
Quick Answer: Will Turning the Thermostat Down Cool Your Home Faster?
No. Your air conditioner has one job: remove heat from your home at a steady rate.
Whether you set your thermostat to 76° or 66°, your AC will cool your home at the same speed. The only difference is how long it continues running.
If your house is 85° and you set the thermostat to 65°, your AC doesn’t suddenly work harder. It simply keeps running until it either reaches 65° or continues running because it can’t reach that temperature in Arizona’s extreme heat.
| Thermostat Setting | Does It Cool Faster? | What Happens? |
| Lower from 78° to 76° | No | Runs until it reaches 76° |
| Lower from 78° to 68° | No | Runs much longer |
| Lower from 78° to 65° | No | May run continuously on very hot days |
| Leave at desired temperature | Best | Maintains consistent comfort and efficiency |
Why Doesn’t My Air Conditioner Cool Faster?
Most residential air conditioners have one cooling speed. Once your thermostat tells the system your home is warmer than the desired temperature, the air conditioner turns on and begins removing heat at its designed capacity.
Think of it like filling a bathtub with one faucet. Turning the faucet “more on” isn’t an option. The water flows at the same rate until the tub is full. Your AC works the same way.
Lowering the thermostat doesn’t increase cooling power. It simply tells the system not to shut off as soon.
Why Do People Think It Works?
It’s easy to assume a much lower thermostat setting will “kick the AC into high gear.”
In reality, homeowners often lower the thermostat because they’re uncomfortable and want immediate relief. Eventually the house does cool down, but it would have cooled at exactly the same rate if the thermostat had been set to the actual temperature they wanted.
The lower setting simply causes the system to continue running longer after it reaches a comfortable temperature.
Can Lowering the Thermostat Increase My Energy Bill?
Yes. One of the easiest ways to increase your summer electric bill is by setting the thermostat significantly lower than necessary. Every extra hour your air conditioner runs uses electricity.
In Arizona, where AC systems already operate for much of the day during the summer, unnecessarily long cooling cycles can noticeably increase monthly energy costs.
Instead of constantly adjusting the thermostat, choose a comfortable temperature and allow your system to maintain it.
What Is the Best Thermostat Setting in Arizona?
There’s no perfect temperature for every household, but many Arizona homeowners find a good balance between comfort and efficiency around:
- 76° to 78° when you’re home
- 80° to 82° when you’re away
If you have a programmable or smart thermostat, setting automatic schedules can improve comfort while reducing unnecessary energy use.
The best setting is ultimately the one that keeps your family comfortable without causing your air conditioner to run longer than necessary.
My House Isn’t Cooling Down. What Should I Do?
If your AC runs for hours and your home still won’t cool, simply lowering the thermostat isn’t the answer. Instead, check for signs that something may be wrong with your system.
Common causes include:
- Dirty air filter
- Dirty outdoor condenser coil
- Low refrigerant
- Frozen evaporator coil
- Blocked air vents
- Aging air conditioner
- Poor attic insulation
- Air leaks around windows and doors
At Norris Air, our ac tune up Mesa experts often find that homeowners assume their thermostat is the problem when the real issue is a maintenance or repair concern that’s preventing the system from cooling efficiently.
Is It Normal for My AC to Run All Day During an Arizona Summer?
Sometimes, yes. When outdoor temperatures reach 110 degrees or higher, it’s completely normal for your air conditioner to run for extended periods, especially during the hottest part of the afternoon.
However, your home should still remain close to your thermostat setting.
If the indoor temperature continues climbing or your system never catches up after sunset, it’s time to have your air conditioner inspected.
How Can I Cool My Home Faster Without Lowering the Thermostat?
If your home feels warm, there are things you can do to keep your house cooler without lowering the thermostat, such as:
- Replace dirty air filters.
- Keep blinds and curtains closed during the afternoon.
- Use ceiling fans to improve air circulation.
- Avoid using ovens during the hottest part of the day.
- Seal gaps around doors and windows.
- Schedule annual AC maintenance.
- Make sure your outdoor unit has plenty of airflow.
Small improvements throughout your home often have a much bigger impact than simply lowering the thermostat.
Trust Norris Air to Keep Your Arizona Home Comfortable
If your air conditioner struggles to keep your home cool, the thermostat may not be the problem.
Whether your system needs maintenance, repairs, or replacement, the experienced technicians at Norris Air can diagnose the issue and recommend the right solution.
If your AC isn’t keeping up with Arizona’s heat, contact Norris Air today to schedule an inspection.
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Frequently Asked Questions
Does lowering the thermostat cool your house faster?
No. Your air conditioner cools at the same rate regardless of the thermostat setting. Lowering it simply causes the system to run longer.
What happens if I set my thermostat to 65 degrees?
Your air conditioner will continue running until it reaches 65°, or it may run continuously if outdoor temperatures prevent your home from ever reaching that setting.
What is the best thermostat setting for summer in Arizona?
Most homeowners find 76° to 78° provides a good balance between comfort and energy efficiency while home, with 80° to 82° being a common setting when away.
Why won’t my house cool down even though the AC is running?
A dirty filter, refrigerant leak, frozen coil, dirty condenser, aging equipment, or poor insulation could all prevent your home from cooling properly.
Does constantly changing the thermostat save money?
No. Frequently adjusting the thermostat usually causes longer cooling cycles and can increase energy usage. A consistent temperature or programmable schedule is typically more efficient.