There are many aspects of a car that drivers need to pay close attention to, but as the weather begins to heat up perhaps none are more important than the air conditioning. Those who have driven in a car with no A/C know it can be a miserable experience, so drivers who have noticed that their cooling isn't up to par should be sure to address this issue before the summer begins.
The most common cause of poor cooling in an A/C system is a lack of refrigerant, which is called R-134a in modern vehicles. Refrigerant is necessary to achieve the cooling effect in a vehicle or else the system will simply blow out warm air. If your fans are working correctly but the car is simply not getting cool, this is likely your problem.
Refrigerant exists in both a gas and liquid state while it travels through the air conditioning system, so there are numerous points where it can escape from the vehicle. It's not uncommon for a vehicle to naturally lose R-134a over time, as hoses may develop microscopic pores that allow refrigerant to seep out. Still, it's important that drivers check for a leak in their air conditioning system before they simply refill the unit with more R-134a.
Many auto parts stores will sell a solution that will cause the refrigerant to change colors. This can make it very easy to spot a leak, as the refrigerant will be visible as it escapes the system. Follow the instructions on the individual product you purchased, as each works slightly differently. Unfortunately, if the vehicle does have a leak, you'll need to bring the car to an expert to have it fixed. Air conditioning systems can be complex and even dangerous to work on, and those handling refrigerant need to be certified to do so.
If there's no leak, you can use a gauge to take a PSI reading on the low-pressure valve. The range you're looking for varies and depends on the temperature outside. On an 80 degree day, look for 56 PSI or higher. A 90 degree day will likely be 70 PSI or higher. If it's lower than these numbers, you'll likely need to add more refrigerant, which will have to be handled by a certified technician.
It's important that you rule low refrigerant out first, because the second most-common cause of A/C problems is the compressor. This device essentially starts the entire cooling process. Turn on your car and air conditioning, then pop the hood. The compressor is a circular object that will be connected to large steel and rubber hoses. If you can't find it, check your owner's manual for its exact location.
The center of the compressor features an inner hub that should turn when an electric clutch is engaged. Many modern cars have a shut-off switch that will prevent the hub from turning if the refrigerant is too low, which is why it's important to address that first. However, there are a number of other reasons the compressor may not be turning, including a blown fuse, faulty wiring, or even a problem with the switch on the dashboard.
If the problem is not related to the compressor or the refrigerant, it's something that an expert will need to diagnose, as taking apart the system will require handling refrigerant. Air conditioning systems are complex and notoriously difficult to access on vehicles, so finding the cause of the issue is something that should be left to a professional.