Why does my air conditioner work at night but not during the day?

Author: Cleora Heller  |  Last update: Sunday, January 4, 2026

Another sign of a refrigerant leak is if your home stays cool at night or on cool days, but won't ever get cool on hot days. It's imperative to turn your AC unit off immediately and call a professional for AC repair in Phoenix if your unit is leaking refrigerant.

Why does my AC work at night but not during the day?

Temperature Differences: Nighttime temperatures are typically lower, which can affect the cooling load on the HVAC system. If the system is not properly calibrated, it may run differently at night, potentially leading to tripping due to overloading or short cycling.

Why is my AC not cooling during the day?

If your AC is running but not cooling, it could be due to a dirty air filter, incorrect thermostat settings, a malfunctioning thermostat, a refrigerant leak, dirty condenser coils, blocked vents or ducts, a faulty compressor, frozen evaporator coils, or electrical issues.

What is the 3 minute rule for air conditioners?

Depending on the system, an optimal time of 3 minutes is required before switching the system on. If the system is turned on without waiting for at least 3 minutes, the system can start with a pressure load. This pressure load prevents the system from cooling properly, which could affect the system in the long run.

Why does my AC stop working after a hot day?

It can be caused by any one or a combination of reasons including refrigerant loss, plugged filters, and clogged cooling fins. The filters and fins you can take care of, the refrigerant needs a professional. Sometimes they go to hell all at once. This is usually a broken fan, or burned out fan or compressor motor.

Why my AC stops cooling after some time?

How do I reset my central AC not blowing cold air?

Use these tips to reset an air conditioner using the reset button:
  1. Turn your thermostat to the “off” setting.
  2. Turn off the circuit breaker that powers your AC.
  3. Press and hold the reset button for three to five seconds.
  4. Restore power to your AC by flicking the circuit breaker back on.

How long should an AC compressor run before shutting off?

When things are working right, your central air conditioner should run for 15 to 20 minutes and then turn off for a few minutes. It will do this two or three times every hour. It may run longer when it's sweltering outside.

Do air conditioners need to rest?

Allowing your air conditioner to rest is an excellent way to extend its life and ensure it operates efficiently throughout the years. Air conditioners, like homeowners, require rest in order to recover and perform optimally.

What is the new law for air conditioners?

The New Regulations

Starting January 1, 2025, all new residential air conditioners and heat pumps must utilize A2L refrigerants. Older refrigerants like R-410, which are likely the refrigerant used by your current system, are being phased out.

What is the first thing to check when the AC stops working?

Check these issues when the unit won't kick on: Check the thermostat and adjust the settings if it isn't set to Cool and an appropriate temperature setting to call for cooling. Examine the house circuit breakers for the AC unit and reset any tripped breakers. Check the air filter and replace the filter if it's dirty.

Is 72 a good temperature for AC?

Setting your air conditioning to 72°F is generally considered a comfortable indoor temperature for many people. It strikes a good balance between comfort and energy efficiency, making it a popular choice for residential settings.

Should I turn off AC if it's not cooling?

When you notice that your air conditioner isn't cooling, your first action should be to turn it off. This might seem counterintuitive—after all, you want your home to be cool. However, continuing to run an AC that isn't effectively cooling can cause further damage to the system.

How cool should my house be if it's 100 outside?

For many of us, 70 degrees is the ideal indoor temperature, but when it is close to 100 degrees outside, your AC unit will be working quite hard to meet these expectations. Consider setting your thermostat at 75 degrees to 80 degrees in your home if the outside temperature is approaching triple digits.

How do I know if my AC is cooling properly?

It's cooler inside: One of the simplest ways to check if your air conditioning unit is cooling your home is to assess the indoor temperature. If it's cooler inside than outside, your air conditioning system is likely functioning correctly.

Why does my AC work sometimes and not other times?

AC Works Intermittently: When the air goes from cool to warm to cool again, you're experiencing intermittent problems. This is often due to a clog in the system, a failed compressor or compressor clutch, a faulty condenser fan, a clog in the system, or the actuator directing airflow has failed.

What is the 3 minute rule for aircon?

Allow a 3-minute break after turning the AC on or off and reset the circuit breaker 24 hours prior to first use to prevent damage and improve efficiency. Perform a pre-start inspection by cleaning the unit, checking filters and coils, and starting the AC in fan mode before cooling to ensure it runs smoothly.

How many hours per day should AC run?

On an average summer day, a general guideline is that your AC should operate between 12 and 16 hours. However, several factors can influence this, including the outdoor temperature, desired indoor temperature, the size and type of your unit, and your home's energy efficiency.

How long should I leave my AC off to reset it?

After finding the circuit breaker for your AC unit, flip it to the off position. Leave it off for around 30 minutes, then flip it back to the on position. If you have fuses, you can only reset the AC by taking the fuse out.

What is the life expectancy of an AC compressor?

Your air conditioner compressor should last the whole lifespan of your air conditioner, about twelve years or more if you choose a ClimateCare air conditioner. However, it might not last that long if your air conditioner is too small for the space it's cooling, or if you don't keep your air conditioner well-maintained.

How often should AC kick on and off?

Typical AC Cooling Cycles

An AC that works will typically perform two or three cycles an hour. On moderately hot days, your AC should typically only run for 10-15 minutes to cool your house thoroughly. This means it will often run for around 10 minutes before shutting off and then stay off for about 10 minutes.

How do I know if my AC compressor is going out?

What are some symptoms of a failing AC compressor? Loud noises, hot air, airflow issues, uneven cooling, and electrical problems are all things you might run into when an AC compressor is on its last leg.

How do I know if my air conditioner needs a new compressor?

Airflow is lower: Lower airflow coming from the air conditioner often means a weakening compressor. The AC is overheating: Are you experiencing frequent circuit breaker trips when the AC is on? This often means the compressor motor is overheating and overloading the circuit breaker.

Why is AC not blowing cold air?

First, check your filters and coils for dirt and debris that may be impeding airflow. Once you've cleaned the filters and coils, run the air conditioner with just the fan so that the ice accumulation can melt off. If the AC still doesn't blow cold air, it could be that refrigerant levels are too low.

Will an AC fan run if the compressor is bad?

While your AC fan may continue to run if the compressor is bad, this doesn't mean your system is functioning properly.

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