April 2, 2024

Signs Your HVAC Air Compressor Is Failing

An air compressor is an integral component in every air conditioner and heat pump in St. Louis, MO. Heat pumps and ACs work by transferring heat energy from one medium to another. When running your AC to cool your home, it transfers the heat energy inside it to the ambient air outdoors. This is possible through refrigerant, which can absorb heat energy and facilitate transitions between liquid and gas. The role of the compressor is to pressurize the refrigerant. As it does, the refrigerant temperature rises. That prepares the refrigerant for the condenser, which then moves the heat energy to the ambient air. There’s a lot that can go wrong with a compressor, so let’s explore the indications that something has occurred.

1. Rising Electricity Costs

A spike in your electricity consumption during the cooling season is one of the first signs that your compressor is failing. It can indicate other HVAC problems as well. This is why we encourage homeowners to track their energy usage on a month-to-month and year-to-year basis. If you experience a sudden spike when running your air, call a technician.

The compressor is one of the primary power draws in an HVAC system. Just having dirty condenser coils can increase your system’s energy consumption by as much as 30%. If a compressor is failing, which leads to inefficient operation, including long cycling, that number can jump a lot higher.

2. Increased Humidity

If you notice your home getting cool but more humid than normal, this may indicate a compressor problem. One issue is short cycling. This means that the compressor is not running at the length it should to achieve the proper relative humidity. It can happen because you’ve sized your AC unit incorrectly. If it happens suddenly, it may be due to a clogged HVAC filter, frozen evaporator coils, or a refrigerant leak. If the compressor is failing, the cycle can be the right period but irregular in its process.

3. Unusual Noises

Unusual and/or loud noises can often be among the first indications of a failing HVAC compressor. The nature of the noise can sometimes give insight into what is wrong. A well-functioning compressor should hum when it’s running. If you hear ticking or clattering when it turns on or off, this can indicate a failing electrical relay. It can also mean that the compressor is simply getting old and may be about to fail.

If you hear rattling or rumbling, this generally means that the motor mount is loose. The good news here is that, if you catch it early enough, it’s typically a relatively easy fix. Your HVAC technician will just need to tighten the screws or, in the worst case, replace the mount. Hissing, whistling, screaming, or screeching indicates that the pressure in the compressor is too high. You should also shut off your system immediately and call in the pros if you hear any banging or grinding. It can indicate not only a mounting issue but also a bad bearing or loose scroll.

4. Circuit Breaker Tripping

An AC or heat pump consumes a significant amount of electricity. These appliances draw the most power when they first start up. This surge of power is what is likely to trip a circuit breaker. If your HVAC and electrical systems are in good condition, a tripping breaker should not occur. That said, an isolated tripping breaker is usually not a concern. It may be due to a power spike or surge that originated somewhere else within or outside of the electrical system.

If a circuit breaker continues to trip when the AC or heat pump kicks on, this is a serious problem. You should not continue to run the system. Call a professional right away. The issue could be that the circuit breaker itself is failing. More likely than not, it indicates a failing HVAC component, and the compressor is a usual suspect. HVAC technicians refer to this as a hard start. Some people describe it as the air conditioner or heat pump shuddering when it turns on.

Hard starts can happen for several reasons. In worst case scenarios, the compressor is failing, and you’ll need to replace it entirely. It can be an issue with the wiring between the fan and electrical panel. In some cases, it may be an issue with the refrigerant line instead.

5. Excessive Vibration on Startup

An AC compressor should vibrate to some degree. This is the hum you hear. If the compressor is vibrating more violently than that on startup, that is a hard start. It may not be causing a tripped circuit breaker just yet, but it will likely get to that point eventually. If caught early enough, a technician may be able to fix it by replacing a failing capacitor or motor component.

6. Changes in Airflow

There is also a direct correlation between your compressor and the airflow and temperature in your home. A potential sign of a failing compressor is air not flowing as forcefully out of your vents as it normally does. If you put your hand to the vent, the air may feel warm or room temperature rather than cool. Temperature issues may also not be as direct. You may, for instance, have a home that feels mostly cool but experiences warm spots in certain rooms. Note that, if you have a heat pump, you can also experience cold spots when heating your home.

7. Leaking Around the Outdoor Unit

Your HVAC condenser is typically outdoors. This is the main component of your outdoor unit. If you notice any liquid accumulating around the unit, you should turn the system off and call a technician. The liquid you see could be refrigerant leaking from the system. Many homeowners expect refrigerant to appear a certain way, but at times, it may simply look like water.

8. AC Won’t Turn On

There are several reasons an AC unit won’t turn on at all, and a failed compressor is one of them. A failing compressor can also result in intermittent trouble. If you have a heat pump that turns on sometimes but not others, this is often a compressor issue. Sometimes the fan may be running, but nothing else seems to be functioning. This can be a compressor issue as well.

9. Overheating

An overheating compressor can cause many of the issues discussed above. It can also result in an AC unit that shuts down mid-cycle. The system may not turn back on immediately, only to turn back on later. If an AC does shut down mid-cycle, you should disable the system via the disconnect switch. Then, call your local HVAC provider.

HVAC Expertise in St. Louis and Beyond

Scott-Lee Heating Company has been repairing and replacing HVAC air compressors throughout St. Louis and the surrounding areas since 1978. Our NATE-certified technicians install, maintain, and repair air conditioners, heat pumps, furnaces, and ductless mini splits as well. We also have indoor air quality experts that install air purifiers, energy recovery ventilators, dehumidifiers, and humidifiers. Contact us today to learn more about these products and services or to schedule an appointment or in-home consultation.