How Does an HVAC Compressor Work?: 2025 Overview
When you think about staying cool in the summer or warm in the winter, your HVAC system likely comes to mind. But have you ever wondered what makes this system tick?
At the heart of your HVAC system is the compressor—a crucial component that keeps your home comfortable year-round. Understanding how it works not only helps you appreciate your HVAC system but can also guide you in maintaining it properly.
KEY TAKEAWAYS
- The compressor is the "heart" of the HVAC system, responsible for circulating refrigerant through the refrigeration cycle. This enables the system to efficiently absorb and release heat, maintaining desired indoor temperatures year-round.
- The compressor drives the refrigeration process in four stages—compression, condensation, expansion, and evaporation. It draws in low-pressure refrigerant gas, compresses it to raise its pressure and temperature, and sends it to the condenser to release heat.
- Proper maintenance is essential to prolong the life of the compressor. Key practices include cleaning the outdoor unit, replacing air filters, and scheduling regular HVAC maintenance.
What is an HVAC Compressor?
The compressor is often referred to as the "heart" of the HVAC system, and for good reason. Just like a heart pumps blood through your body, the compressor circulates refrigerant through the HVAC system.
Refrigerant is a special fluid that absorbs and releases heat as it changes states (from gas to liquid and back again). The compressor ensures this process keeps happening efficiently.
How Does It Work?
The compressor operates as part of a larger refrigeration cycle, which consists of four main stages: compression, condensation, expansion, and evaporation. Here's a step-by-step breakdown of what happens inside the compressor:
1. Drawing in Refrigerant Gas
The cycle begins with the compressor drawing in low-pressure, low-temperature refrigerant in its gaseous form from the evaporator. This gas is loaded with heat absorbed from your indoor air.
2. Compressing the Gas
Using mechanical energy, the compressor squeezes the refrigerant gas, significantly increasing its pressure. As the pressure rises, so does its temperature. The result? The refrigerant becomes a high-pressure, high-temperature gas.
3. Sending the Gas to the Condenser
The high-pressure, high-temperature gas is then sent to the condenser coil (usually located outside your home). Here, the refrigerant releases the heat it absorbed earlier, allowing it to cool down and change into a liquid state.
4. Completing the Cycle
After leaving the condenser, the refrigerant moves through the expansion valve and evaporator coil, repeating the process of heat absorption and release. The compressor keeps this cycle going, ensuring your HVAC system maintains the desired indoor temperature.
Types of HVAC Compressors
Not all compressors are the same. Depending on your HVAC system, you might encounter one of the following types:
- Reciprocating Compressors: Use a piston and cylinder to compress refrigerant, similar to how a car engine works.
- Scroll Compressors: Employ two spiral-shaped components, one stationary and one moving, to compress the refrigerant.
- Rotary Compressors: Feature rotating blades or vanes to compress the refrigerant, often used in smaller systems.
- Screw Compressors: Use two interlocking screws to compress the refrigerant, ideal for large-scale systems.
- Centrifugal Compressors: Utilize a spinning impeller to compress the refrigerant, often found in industrial settings.
Signs of a Faulty Compressor
Like any mechanical component, compressors can wear out over time. Watch for these warning signs:
- Warm Air Instead of Cool: If your AC is blowing warm air, the compressor might not be functioning properly.
- Loud or Unusual Noises: Banging, rattling, or humming noises could indicate compressor trouble.
- Frequent Cycling: Short cycling (when the system turns on and off repeatedly) might signal a compressor issue.
- High Energy Bills: A failing compressor can lead to inefficient operation, driving up your energy costs.
If you notice any of these issues, it’s best to schedule HVAC repair service to have a Sears Home Services technician check your system and repair the problem.
Maintaining Your HVAC Compressor
To keep your compressor running smoothly:
- Clean the Outdoor Unit: Ensure the condenser coil and surrounding area are free of debris to prevent overheating.
- Replace Air Filters Regularly: Dirty filters restrict airflow, putting strain on the system, including the compressor. Replace air conditioner filters monthly or as required by guidelines in the owner’s manual.
- Dust and Wipe Down Vent Grills: Dust can accumulate on your vent grills, which can impact airflow. A quick wipe with a damp cloth will keep them clean and ensure that air circulates freely.
- Schedule Regular Maintenance: Professional HVAC maintenance will keep your system operating efficiently and can identify and resolve potential problems before they escalate. Schedule an HVAC system tune-up yearly.
Here’s a YouTube video that shows how our Sears Home Services technicians complete HVAC maintenance:
Annual HVAC preventive maintenance will also help keep your compressor and entire heating and cooling system lasting longer.
Sears Home Services is always ready to help you keep your HVAC system in top shape. We have the best qualified and most experienced technicians in the industry.
Trust Sears Home Services will all of your heating and cooling system needs.
Frequently Asked Questions
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Glossary Terms
A heat pump is an energy-efficient device that transfers heat from one place to another, providing heating in the winter and cooling in the summer.
A dual inverter air conditioner incorporates advanced inverter technology with two rotary compressors, providing ultra-efficient cooling with minimal noise and energy consumption. This innovation offers a significant leap in air conditioning technology, providing precise temperature control and longer-lasting performance.
A ductless air conditioner, often referred to as a mini-split, is a highly efficient cooling system that operates without the need for extensive ductwork, making it ideal for space-specific cooling and homes without existing ducts.
A humidifier is a device designed to increase humidity levels in a single room or an entire building, improving air quality and comfort.
Common Appliance Symptoms
The most common reasons your Kenmore Elite refrigerator stopped working are a locked compressor, damaged evaporator or a defective electronic control board.
The most common reasons your Maytag refrigerator stopped working are a locked compressor, damaged evaporator or a defective electronic control board.
The most common reasons your Bosch dishwasher has no heat are a defective electronic control board, clogged water valve or a broken detergent dispenser.
The most common reasons your Kenmore Elite microwave has no power are a bad thermostat, malfunctioning electronic control board or a broken switch.
The most common reasons your Kenmore refrigerator is noisy are a faulty ice maker assembly, defective electronic control board or a locked compressor.
The most common reasons your LG freezer is leaking water are a clogged drain tube, cracked water tubing or a bad evaporator.