Just like you take your car in for routine tune-ups and hit the gym to stay healthy, your AC system needs regular attention too.

But when does it make sense to repair versus replace your AC system? To answer that, consider your air conditioner’s age and current performance level.

1. Heat Pumps

The best way to save energy, cut emissions and keep your home comfortable is with a heat pump. These super-efficient systems combine heating and air conditioning into one system. They work by using the refrigeration cycle to mechanically transfer heat, drawing warmth from the air outside and moving it indoors to heat your house, or in reverse to withdraw hot air from the house to cool it. Unlike furnaces, which burn fuel to create heat, heat pumps use electricity to do the job, with gas acting as a backup for very cold days and to dehumidify when necessary.

Because of their high efficiency and ability to run on electricity generated by renewable sources, these systems are increasingly popular in homes across the country. They’re also a good choice for businesses considering the long-term impact of carbon emissions on climate change.

Despite their energy efficiency, however, heat pumps can suffer from problems similar to those of conventional HVAC equipment. If you’re experiencing any of the common heat pump issues listed below, you should call for service.

Running constantly

If your heat pump runs continually, it may be overworked due to insufficient airflow or improper sizing. If you suspect this is the case, ask your technician to perform a Manual J load calculation based on an accepted method (Air Conditioning Contractors of America) for your region.

Running but not cooling

If the heat pump is running but not cooling, it could be that the thermostat isn’t set to the right temperature or that it is in air conditioning mode instead of heating mode. It’s also possible that the reversing valve, which moves warm air from inside your house to outside (when the heat pump is in heating mode) or cools the warm air from outside back into your home (in cooling mode), needs replacement.

Rattling sounds

A rattling sound can indicate a loose component or part that is hitting something else in the unit, such as the fan or compressor. A technician can inspect the system to check everything and tighten any loose screws.

2. Furnace

While you can handle a few maintenance tasks yourself, such as replacing the air filter and vacuuming your return and supply vents, it’s best to leave most furnace-related issues to professionals. Annual inspections catch small problems before they become major ones and can save you money over time.

Furnaces heat ductwork and blow it into different rooms in your home through a series of registers. They work in tandem with a room thermostat and a heating control system to provide you and your family with warm and comfortable indoor temperatures.

The thermostat detects when your home temperature drops, then sends a signal to the heating control system to switch on your furnace. A blower housed in a structure called the air handler then switches on and circulates the heated air through your ductwork system.

Your furnace operates on a liquid fuel, such as natural gas, propane, liquefied petroleum gas (LPG), oil or, for a short period of history at the turn of the 20th century, whale oil. The burner area and heat exchanger of a gas-powered furnace operate in conjunction with the pilot light, ignition system and flame sensor.

Once the gas in your furnace is ignited, it combusts and forms warm air and combustion byproducts that travel through the heat exchanger into your home’s ductwork. These byproducts are vented out the flue or chimney to keep your home and the surrounding environment safe and sanitary.

Modern high-efficiency gas furnaces boast a combustion efficiency rating of 90% or higher, meaning that the majority of the fossil fuel energy goes into warming your home rather than being wasted up the flue or in other inefficient ways. Older furnaces, on the other hand, typically have a much lower AFUE (annual fuel utilization efficiency), which can be as low as 40%.

A malfunctioning furnace can produce a wide variety of strange noises and symptoms, including odors, vibration or even leaking gas. If you notice these signs, shut off the power to your furnace and call a professional immediately.

3. Ductless Systems

Ductless systems can heat and cool your home just as well as central air conditioning, but they’re a lot more affordable. They are also great for new additions to your home, as they can be installed in rooms without existing ductwork. Also known as ductless mini-split or ductless multi-split, these units have an outdoor compressor/condenser unit, and an indoor air-handling unit. Power cables, refrigerant tubing and suction tubing run between the two units, allowing them to heat or cool each room separately. Many ductless systems can even provide supplemental heating, as they are also what is called a heat pump.

One of the biggest advantages of a ductless system is that you won’t have to worry about losing cooled air due to leaking ducts, as duct leakage is a common problem with centralized air systems. Ductless systems are also easier to maintain, since the units can be easily cleaned. Just like any other air conditioner, the units need to be kept clean in order to maintain optimal performance.

Adding a ductless system to your home is also much more cost-effective than installing a new central air system, as you’ll save on the costs of repairing or replacing damaged or outdated ductwork. The installation is also a lot quicker and less messy, since there’s no need to tear down walls and other major construction.

Ductless air conditioners are also environmentally friendly, as they use R410A refrigerant that has no ozone depletion potential. They are a great choice for homes that can’t accommodate ductwork, and they also work well in new additions such as sunrooms or garages.

You’ll also save on your energy bills, as ductless systems are far more energy-efficient than central air conditioners. They are ENERGY STAR qualified, and they can save you money on your energy bills by actively cooling or heating only the areas of the house that are occupied. In addition, they have high SEER and EER ratings that can help you get the most out of your investment. They are a great choice for Mississauga homeowners looking to upgrade their home’s HVAC efficiency.

4. Air Conditioners

Most homes in the US have air conditioning, and for good reason. While it’s often seen as a luxury, it is a necessity in many climates and can improve the comfort of your home, reduce stress, and even protect against health issues like high heat and humidity*.

While some AC issues can be dealt with simply by changing a dirty filter or turning off the thermostat for a few minutes, others require a bit more digging. For example, if your air conditioner turns on and off continuously during hot summer days or makes an unpleasant high-pitched screeching sound it’s time to call for repair. The latter issue could indicate that the contactor (relay) or start/run capacitor(s) have failed, both of which are relatively inexpensive and easy to replace.

In addition to these common AC problems, if you notice your electric bill going up every summer it could be a sign that you need to have your system inspected. Depending on the state of your unit and how well it’s been maintained, an upgrade to a new energy efficient model can help you save up to 40% on cooling costs each year*.

You may also need to replace your air conditioner if it’s older than ten years and the warranty has expired. If it’s been well-maintained, however, most cared-for systems can last past 15 years.

Other signs that it’s time to get a new AC unit include short-cycling, which is when the system turns off and on in small spurts rather than keeping your home cool consistently. Another consideration is that your current system isn’t meeting your home comfort needs, such as if it’s undersized for your space or old and inefficient. Getting a new system that’s properly sized for your home can improve efficiency and provide you with the latest technology to help you stay comfortable.