It's easy to take your car’s AC for granted. After all, the system mostly functions without any serious attention on the owner’s part. However, nothing is more frustrating than when that summer heat hits you behind the wheel, and you crank the AC only for nothing to happen.
When temperatures skyrocket, the last thing you want is to melt into the seats because your car’s AC system isn't working. That’s why it’s best to be proactive, and perform a thorough once-over before the heat comes in full swing.
Thankfully, AC inspection is relatively simple—and we’re here to walk you through it. We’ll even provide some repair advice, so you can make sure you'll always stay cool when temperatures rise.
Basic Operation Check
A basic operations check is a great place to start when determining the health of your AC system. By simply running the system through its paces, you can get a really good feel for any potential issues that may be waiting under the hood. It can also provide specific details that will help your mechanic solve any issues that may present themselves.
Best of all, the test we're about to walk you through only requires a few minutes of your time, and the only tool you’ll need is a thermometer.
Turn On the AC
The first part of the process is simply checking that the AC system actually turns on. With the engine running, turn on the system and listen closely to ensure the compressor engages.
These are driven by the engine's serpentine belt, so you should hear a slight drop in the RPM, confirming the compressor is running. A light on the dash may also indicate that the system is on. If it doesn't turn on, you know to inspect the power supply and the compressor for issues such as broken wires, blown fuses, or internal damage to the compressor.
Listen for Any Whining, Hissing, or Grinding Noises
With the AC on and the compressor functioning properly, the next thing to do is listen to the system. It should run smoothly and quietly. Any grinding, whining, or screeching indicates an issue with the pump or belt.
The source of the sounds could be as simple as a slipping serpentine belt that needs to be replaced or bad bearings in the condenser, which may warrant replacing the entire unit. If you hear a hissing sound, it could be pressurized refrigerant escaping the system through the pressure-relief valve or due to a leak, indicating repairs are needed.
Pay Attention to Your Nose
Another sense to pay attention to when performing an AC system inspection is your sense of smell. Issues may present themselves with a foul odor that helps you pinpoint the source. Smells of burning rubber can indicate an issue with the pump bearings or serpentine belt, while a sweet, coolant-like smell is a sign of a refrigerant leak.
Check AC Temperature
The final thing to check is that the AC is cooling the air properly. This is where your thermometer comes in. Let the system run for a few minutes to get a good reading, then use your thermometer to take the temperature.
As a general rule, the air coming out of the vents with the AC running should be 30-35 degrees Fahrenheit cooler than the outside temperature. If it's any warmer, it could be a sign that your AC needs to be recharged. If it doesn’t cool the air at all, there may be a leak present.
Under-Hood Inspection
Even if no issues present themselves during the operational check, you should follow up by taking a closer look at the system components to ensure everything is in good health.
Start by looking for signs of potential issues that allow you to work proactively or to address any problems that popped up during your operational check. For example, any signs of cracked lines or physical damage are your cue to replace that part. Otherwise, they can fail at any given moment, leaving you without AC.
The good news is that if you suspect a leak, it'll be easy to spot. The refrigerant is dyed green to help specifically with this. So, if you see any green residue on any AC parts, you know where the leak is coming from and can replace the faulty component.
Once you finish looking everything over, it's best to follow up with an AC manifold test if your system isn't performing properly. These testers are designed to give you a reading on both the high and low sides of the system to ensure pressures are within normal ranges. It’s an effective way to spot any issues within the system, or to tell you for sure that it needs to be recharged.
It's important to keep in mind that AC systems contain refrigerant, which is harmful to both you and the environment. If you find any issues that need to be addressed but refrigerant is still in the system, it will need to be evacuated properly before proceeding. This requires specialty equipment, and you'll likely be better off letting a professional handle it.
Replacing cracked lines and other damaged components that have already allowed the refrigerant to escape are things you can do yourself, but something like a faulty compressor or system blockage is better off being taken in to a shop.
Recharging the System
Having low refrigerant levels is the most common issue causing poor AC performance, but that’s nothing to get upset about. It’s not going to cost hundreds of dollars to sort out. In fact, you can opt to recharge the system yourself with some easy-to-use and cheap equipment.
If you do determine a recharge is needed, all you need is an AC recharge kit and about five minutes of your time.
These kits contain a can of refrigerant (which you need to match up to the type used in your vehicle), a hookup that you attach to the low-pressure side of the AC system, and a gauge that gives you a reading on charge levels. This gauge can also be used to help troubleshoot other issues that you may have missed.
With the vehicle and AC system running, simply hook up the kit, check the gauge to ensure low refrigerant is the issue, and then dispense refrigerant into the system until the gauge reads the appropriate range. After that, you're back to having cool AC for years to come!