How does AC work step by step?

Air conditioning (AC) is a technology that removes heat and humidity from the air, providing a comfortable indoor environment. The process of air conditioning involves several key steps that work together to cool and dehumidify the air. Here's a detailed, step-by-step explanation of how AC systems function.

The Refrigeration Cycle

The core of an AC system is the refrigeration cycle, which uses a refrigerant to absorb heat from the indoor air and release it outside. The key components of this cycle are the compressor, condenser, expansion valve, and evaporator. The refrigeration cycle works as follows:

1. The compressor pressurizes the refrigerant, causing it to heat up.


2. The hot, high-pressure refrigerant then flows into the condenser, where it releases its heat to the outside air, causing the refrigerant to condense into a liquid.


3. The liquid refrigerant then passes through an expansion valve, which reduces its pressure and temperature.


4. The cold, low-pressure refrigerant then enters the evaporator, where it absorbs heat from the indoor air, causing the air to cool down. This cooled air is then circulated back into the building.


5. The refrigerant, now in a gaseous state, returns to the compressor to repeat the cycle.

This continuous refrigeration cycle is what allows an AC system to continuously remove heat from the indoor air and release it outside, providing cooling and dehumidification.

Air Circulation and Filtration

In addition to the refrigeration cycle, AC systems also include fans and ductwork to circulate the air throughout the building. The key steps in the air circulation and filtration process are:

• The indoor fan draws warm, humid air from the building into the AC unit.


• This air passes over the cold evaporator coil, where heat and moisture are removed.


• The now cooled and dehumidified air is then pushed back into the building through the ductwork by the indoor fan.


• Air filters in the system remove dust, pollen, and other airborne particles from the circulating air, improving indoor air quality.

The combination of the refrigeration cycle and the air circulation/filtration system is what allows AC units to effectively cool and dehumidify indoor spaces.

Conclusion

In summary, air conditioning works through a complex but efficient refrigeration cycle that removes heat and moisture from the indoor air, combined with fans and ductwork that circulate the cooled, filtered air back into the building. This multi-step process is what allows AC systems to provide comfortable, climate-controlled indoor environments.

How does an air conditioner work step by step?

An air conditioner works by pulling warm air from a room, passing it over cold evaporator coils filled with refrigerant, which absorbs the heat. The refrigerant is then pumped to the condenser outside, where it releases the heat. The cooled air is circulated back into the room, and the process repeats.

What is the 3 minute rule for AC?

The "3 minute rule" for air conditioners is a recommendation to wait at least three minutes before turning the unit back on after it has been shut off. This allows the refrigerant pressure to equalize, which protects the compressor from damage, prevents electrical surges, and prolongs the system's lifespan. Many modern systems have a built-in 3-minute delay to enforce this rule automatically, but it's still a good habit to follow manually.
 
Why the 3-minute rule is necessary

• Pressure equalization: When an AC is turned off, pressure builds up in the system. Restarting it too soon can cause the compressor to work against this high pressure, leading to excessive strain and potential damage. 
• Compressor protection: The 3-minute wait allows the compressor to operate under an optimal and stable environment, preventing it from getting bogged down or overheating. 
• Preventing damage: Restarting a compressor immediately can lead to electrical surges that damage internal components like the compressor motor. 
• Extended lifespan: By reducing strain and preventing damage, following this rule helps extend the overall life of your air conditioning unit. 

How to follow the rule

• Manual waiting: If you are manually turning your AC off and on, count to 180 seconds before restarting it after a shutdown. 
• Use built-in delays: Many modern thermostats and newer AC units have a built-in delay timer that automatically prevents the unit from restarting for approximately three minutes. 
• Avoid frequent cycling: Adjusting the thermostat too frequently can cause the system to cycle on and off, which is inefficient and hard on the unit. 
• Consider a smart thermostat: If you frequently forget or find it difficult to wait, consider installing a smart thermostat that has a built-in delay feature to protect your system for you. 

What is the $5000 AC rule?

The "AC 5000 rule" is an HVAC industry guideline that suggests replacing an air conditioner if the result of multiplying its age by the estimated repair cost is over $5,000. If the result is under $5,000, a repair is likely the more cost-effective option for now. This is a simple starting point, and other factors like energy efficiency, repair history, and comfort should also be considered before making a final decision.
 
You can watch this video to learn more about the 5K rule: 28sHVAC Guide for HomeownersYouTube · Feb 19, 2025
How to apply the rule

• Multiply: Take the age of your air conditioning unit in years and multiply it by the estimated cost of the repair. 
• Analyze the result:
  • If the total is greater than $5,000: Consider replacing the unit, as it may be more financially sound in the long run. 
  • If the total is less than $5,000: A repair is likely the better option, especially if the system has been reliable up to this point. 

Example

• A 12-year-old unit with a repair estimate of $600: 12×600=$7,20012 cross 600 equals $ 7 comma 20012×600=$7,200. Because this is over $5,000, replacement might be a better long-term investment. 
• A 5-year-old unit with a repair estimate of $500: 5×500=$2,5005 cross 500 equals $ 2 comma 5005×500=$2,500. Because this is under $5,000, a repair is probably the more economical choice. 

Other factors to consider

• Energy efficiency: A new system with a higher SEER rating can lead to significant savings on energy bills. 
• Frequency of repairs: If you are constantly needing repairs, the cost of individual repairs can add up to more than a new system. 
• Refrigerant type: Older units may use refrigerants like R-22, which are becoming more expensive due to being phased out. 
• Warranties: Check for any warranties on new systems or parts before making a decision. 

This video explains how to use the 5K rule for deciding whether to repair or replace your HVAC system: 58sServiceMark Heating Cooling & PlumbingYouTube · Jun 20, 2016

What should my AC be set at if it's 100 degrees outside?

- Although the temperature outside may be near 100 degrees, experts say you should be using what they call the 20-degree rule. That means you should keep your thermostat at 80 degrees when it's 100 degrees outside.