Tips for Technicians

Ever been stuck on a tough repair or spent way too long figuring out a system issue? We’ve all been there. This new blog series is packed with practical advice, smart solutions, and hands-on tips you can immediately use to solve problems faster and work smarter. No fluff—just the information that makes a difference when you're out in the field.

The technical issue most technicians underestimate and/or overlook

Challenges in the Field

In the previous blog in the Tips for Technician series, we looked at how to systematically approach a troubleshooting job. This included steps like making sure the power is working, measuring the temperature around the lines, and checking the refrigerant charge for example. This blog also briefly mentioned the importance of your compressor in the system you’re troubleshooting. This week, we’ll dive in further to understand why the compressor can play a significant role in your troubleshooting process.

First, it’s crucial to understand what a compressor is and what role it plays in the HVACR system. In general, a compressor is a mechanical device that increases the pressure of vapor or air by reducing the volume. In an HVACR system, a compressor ensures that the refrigerant gas, specifically, is compressed— or pressurized — so the refrigerant can carry and release heat.

The compressor is typically located in the outdoor air conditioning unit, often positioned at the back or side of the house or building. Other components within this outdoor unit include the condenser, condenser coil, and fan. The outdoor unit is connected to the indoor section of the air conditioning system via a copper refrigerant line.

The compressor in your system can be considered the heart of the unit. Without the compressor, the system wouldn’t be able to carry refrigerant around, therefore cold or warm air wouldn’t be produced, and your home would either remain too warm or too cold. Simply put, without your compressor, you can’t have an HVACR unit.

As the cooling system operates, the refrigerant shifts from a liquid state to a vapor. Upon reaching the compressor, it is entirely in gaseous form. The compressor then increases its pressure and temperature, making it either hotter or cooler than the surrounding environment, depending on whether the system is in heating or cooling mode.

Next, the pressurized refrigerant moves into the coil designed for heat exchange. In this stage, it either releases or absorbs heat, depending on the system’s function. As it undergoes this process, it transitions back into a liquid state, ready to continue the cycle.

If you find yourself at a job where the compressor is the failing component of the system, it is highly important to not just replace the compressor and ‘finish the job’. To build customer trust, and reduce callbacks, it is essential to find out why the compressor was failing in the first place. Simply replacing the compressor and walking away often won’t fix the issue in the long-term.

A compressor in an HVACR system can fail for several reasons, many of which come down to refrigerant issues, faulty expansion valves, or improper system setup. One of the most important checks is the refrigerant charge—too much or too little can cause faulty operation and increased stress on the compressor. Overcharging can lead to high pressures, while undercharging can cause overheating and oil return problems.

Ensuring the pipework is sized and installed correctly is also critical. Poorly calculated piping can result in pressure drops, oil trapping, and inefficient refrigerant flow, all of which can overwork the compressor and shorten its lifespan. Proper pipe sizing and layout help maintain system efficiency and prevent unnecessary strain on components.

Expansion valves, especially in VRF and VRV systems, are another common failure point. These motor-driven valves control refrigerant flow, and if they malfunction, they can allow liquid refrigerant to flood back to the compressor. Since compressors are designed to handle gas, liquid refrigerant can cause slugging, damage valves, and wash out lubrication, leading to severe mechanical failure.

What are VRF and VRV systems? Variable Refrigerant Flow (VRF) and Variable Refrigerant Volume (VRV) are two different terms for the same type of system. VRF/VRV systems rely on refrigerant as the primary heating or cooling source. These systems also use inverter compressors, which means the compressor is able to run at different speeds to save energy. The terms VRF and VRV are both used to describe the same type of system, but the name VRV is trademarked by Daikin Industries.

Another key factor is the compressor heater, often called a crankcase heater. If it’s not working, the compressor won’t properly warm up before startup, increasing the risk of mechanical failure due to cold oil and improper refrigerant flow. Checking that the crankcase heater is operating as it should, can prevent premature wear and costly breakdowns.

Finally, it’s important to remember that the compressor is more than just a part of the HVACR system—it’s a critical component that can indicate underlying issues when it fails. By understanding the factors that contribute to compressor failure, like improper refrigerant charge, valve malfunctions, and system setup issues, you can troubleshoot more effectively and avoid unnecessary replacements. A successful repair isn’t just about replacing the compressor—it’s about finding the root of the issue to prevent future problems. By taking your time to find the underlying issues, you’ll not only fix the immediate problem but also help ensure the system runs smoothly for the long haul, saving both you and your customers time and money.

Stay tuned for the next part of the Tips for Technicians blog!