How to Make Your Car AC Colder

Air conditioning is the difference between a comfortable drive and a sweltering nightmare when temperatures outside soar. But are there ways to troubleshoot when your car’s AC isn’t quite keeping up? Here are tips for how to make car AC colder.

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How does car AC work?

Let’s take a look at how your AC system should work. Knowing how to make your car AC colder won’t matter if components are damaged and failing.

Modern air conditioning consists of a condenser in the grille, an evaporator near the heater core and a compressor mounted with the engine accessories and a receiver-drier in the plumbing that connects everything. When you turn on the AC, a blower fan forces hot air from the passenger compartment through the evaporator, transferring heat to the refrigerant. The compressor keeps refrigerant circulating, taking heat with it as it flows to the condenser where it cools before circulating back to the interior.

Newer AC systems featuring automatic temperature control use a thermostat to adjust the amount of hot/cold air to maintain the desired temperature. If your AC system is maintained and working as it should, there are a few tips for getting your car AC super cold.

How to make car AC colder

Your AC system works well to cool the interior of your vehicle. Usually. But on super hot days you might wonder if there’s a way to kick it up a notch.

Don’t recirculate air (at first)

When you start your vehicle, turn off the recirculation system. This setting doesn’t pull air from outside—it just blows around the existing cabin air. Because of the greenhouse effect, your vehicle’s interior is hotter than the surrounding air, so blowing it back at you won’t make you cool down. Instead, draw external air and roll down your windows until the car has cooled off.

Change the cabin air filter

If you haven’t changed the cabin air filter in your Pontiac since Pontiac was selling new cars, it’s time. A cabin air filter collects debris in the incoming air but has a limit. If you keep using it when it’s clogged with dust and leaves, the air filter acts as an obstruction, limiting the flow of air. Fortunately, cabin air filters are cheap and easy to replace.

Start with the fan first

When you first start up, just use the ventilation fan. Roll down the windows and set the fan to high. This gets the hotter air out, potentially dropping the temperature by 40 degrees almost instantly. The fan provides air movement that feels cooler, while giving the engine time to reach operating temps without excess engine loads. Once you are in gear and on your way, roll up the windows and turn on the air conditioning for maximum efficiency.

Park (and drive) in the shade

While it’s still hot under a tree or carport, it feels cooler because of the shade blocking the sun’s rays. A car in the sun collects more of the sun’s UV heat, with nowhere for it to go except the car’s interior. By parking in the shade, you prevent this additional heat from getting in your ride. The same goes for your drive. A tree-lined route will always feel cooler than a sweltering highway.

Use the coldest setting

Get in and crank the cold. Why? When you select anything but the coldest AC setting, the system has to mix in some warm air to get it to your selected temperature setting. Cooling the air because you’re hot and then having to warm it up a bit is counterproductive. This extra work is inefficient and doesn’t make you cooler. Selecting the coldest setting only cools the air and sends it on to you. Reduce the fan speed if you start feeling chilly.

Turn off stop-start

Auto start-stop is a neat feature, saving you around 8% in fuel costs compared to driving without it. However, when the engine is off, the accessory drive is off. That used to mean the AC compressor stopped working and you’d get only warm air blowing in the cabin. But modern compressors are electronically driven rather than belt driven to stay running when the engine shuts off. The engine-off AC isn’t efficient, so turn off start-stop when the weather is sweltering.

Don’t try to “pre-cool”

Pre-cooling your car sounds smart, ideally having it nice and comfy before you even get in. Great idea, but all you’re doing is wasting gas. An AC compressor spins at the same speed as the engine, so at idle, the AC system is inefficient compared to on-road revs. Just get in and get going, and you’ll be cooler faster.

Close the passenger vents

If there’s no one in the passenger seat, why are you directing cold air to it? Closing the other vents means the ones blowing on you are the only ones open, increasing the volume of air on you and cooling you faster. If you’re expecting passengers, open the vents a few minutes before they get into the car.

Recharge your refrigerant

Let’s say you really want to know how to make car air conditioner colder with one simple task. This is it. The air conditioning system has several parts, so over the years it is possible and even normal to have the refrigerant find a place to leak out. When that happens, it’s time for a recharge. These simple kits are affordable and easy-ish to use, and they refresh the AC system with new refrigerant.

Note that these are not permanent fixes. Air conditioners are closed systems meant to last the life of the car, so a coolant leak means something’s wrong. A recharge might get you through a summer, but you need to address the bigger issue.

Tint your windows

Untinted auto glass can often magnify the sun’s rays, making your car’s interior even hotter. Tinting the windows can change the aesthetic but also keep your ride cooler on sunny days by blocking more than 90% of UV light, preventing you from melting. It’s also a pretty affordable upgrade.

Reasons your AC still isn’t cold

Let’s say you’ve tried all of the above and the AC in your car doesn’t feel colder. Odds are there may be something wrong with your AC system. In an older car, it could be a combination of factors.

Refrigerant leak

The refrigerant, sometimes called by the old brand name Freon, is the liquid that circulates in the air conditioning system. Like a refrigerator, AC just won’t work without this critical gas. Seals wear out because of aging, getting brittle, cracking and slowly releasing refrigerant. If your AC slowly became inadequate, a refrigerant refill is likely needed. Have a mechanic look for leaks in the system before attempting the refill yourself, or let them handle it all.

Broken condenser

The condenser is located in front of the radiator. Because of its location, the condenser can be damaged by rocks and other road debris. If the condenser takes too much damage or fills with leaves, sticks and rocks, it stops working effectively and can no longer cool the refrigerant. Replacement isn’t recommended for the DIY mechanic—this requires specialized tools to deal with high-pressure lines.

Electrical problems

Complicated electronic components can cause complicated electrical problems. Electrical problems can vary from a blown fuse or failed relay or even a problem at the AC controls. If the AC works normally at the higher settings but not on lower settings, look at the blower motor resistor. If the system does not work at all, check the fuse and then the control panel.

Failing compressor

A compressor is an expensive part, and you’ll definitely notice if it starts to fail. Common signs of compressor failure include an unusual grinding or squealing noise from the engine bay because the AC compressor pulley slows and drags on the accessory belt. There may be a burning smell with your lack of airflow or signs of leakage from the compressor spilling its internal lubricant. Get this checked out by an expert.

Blocked airflow

If the AC feels cold at the vent but there is little or no air movement at any fan setting, you have an air blockage or failed blower motor. Both will cause a lack of air movement in the cabin. For a blockage, check and replace the cabin air filter and stick a shop vacuum to the vents to pull out any debris. A blower motor replacement is a fairly simple repair, but it is also affordable to hand off to a mechanic.