Why is my A/C not blowing cold?

A failed air conditioner is as bad as—or maybe worse than—a dead hot water heater in the winter. No one likes to sit in a sauna on wheels, just like no one enjoys frigid showers. But A/C units do malfunction, so let’s review what can cause a failure, how to have it fixed, and how to reduce the chances of your A/C conking out in the first place. 

Your vehicle’s air conditioner in a nutshell 

In gas-powered vehicles, the engine powers the A/C, which uses an evaporator, compressor, and condenser plus two other components depending on your vehicle: either an expansion valve and receiver/dryer or an accumulator and orifice tube. 

These components circulate a refrigerant through a closed system. It absorbs heat and returns the cooled air to the car cabin. 

Before you take your car in for servicing, ensure you test your A/C while driving. A common misconception is that you can cool down your cabin simply by turning the car on, when you actually need to drive to fully power up your A/C and get that cooler air circulating. 

A/C refrigerant leak 

Refrigerant circulates through your A/C system, expanding into a gas and contracting into a fluid as it removes heat and humidity from the cabin. In its gaseous state, it can leak through the smallest cracks in the system without you noticing. As a fluid, refrigerant can look oily, so look for oily patches around the air conditioner. 

A loud, continuous clicking sound when the A/C is running could be an alert that you have a refrigerant leak. Without the correct refrigerant levels, the A/C can’t function correctly. 

Your vehicle’s evaporator coil 

The evaporator coil is a set of pipes over which air is blown to cool. These pipes are filled with refrigerant, which changes from liquid to gas as it absorbs the heat from the air. Warm air blowing out the vents can signal a problem here. 

Clogged condenser 

To cool the refrigerant again, the A/C system passes it over another set of coils called the condenser. As its name implies, it condenses the gaseous refrigerant back into its liquid state. 

A clogged condenser can’t cool the refrigerant, preventing it from absorbing heat from the vehicle cabin. 

Your hint for this problem is a rattling noise when you turn on the A/C. You may be able to remove accumulated debris from the condenser yourself—you’ll find it between the radiator and front grille. 

Broken compressor 

The compressor acts as a bridge between the evaporator and condenser by taking the refrigerant in its low-pressure gaseous state and compressing it into high-pressure gas. You’ll find it in front of the engine. If it breaks down, the refrigerant can’t reach the condenser to be cooled. 

Signs you have a broken compressor include warm or hot air blowing into the cabin and unusual noises when you turn on the A/C. 

Electrical system issues 

If the A/C components are all in good condition, an electrical issue – such as a frayed wire or blown fuse – may be causing the hot air, or the A/C system might need to be recharged. Although you can recharge your A/C at home, it requires purchasing specialized equipment. It’s also not a procedure for the beginner DIYer or for someone who simply wants to save a few dollars. 

Keep in mind A/C systems made before 1995 typically can’t be recharged. 

How can I maintain my car’s A/C? 

To avoid expensive repairs, you can help your A/C stay in good condition with these tips. 

Pay attention to the settings on your thermostat. Especially hot temperatures are not a time to crank up the A/C by setting it to 20˚C. Instead, aim for “comfortably warm,” such as 23.5˚C. This will let you stay cool and save your A/C the excessive work associated with trying to reduce interior temperatures to half of what they are outside. 

Whatever the weather, run your A/C on defrost mode for 10 minutes each week throughout the year on the coolest setting, with the fan at maximum speed. This will help maintain gas pressure and keep the compressor running well. 

Owners of gas-powered vehicles shouldn’t pre-cool their car: the A/C operates at maximum efficiency while you’re driving. To avoid getting into an oven when you first set out, open all the car doors and turn on the fan. This will get the super-hot air out and the air circulating. Turn on the A/C once you’re driving. 

If you drive an electric vehicle, we advise pre-cooling it while it’s charging, because this will help with battery efficiency. You’ll also save valuable battery energy for the road. 

Clean or replace the cabin air filter at least once every 12 to 24 months (12 to 18 months for an EV). 

Pay attention to any changes in your A/C system, including strange noises, smells, or warm air. If you notice any problems, drop by your local NAPA AUTOPRO service centre for expert advice. To learn more about recharging your air conditioner, read this

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