Now is not the time! You climb into what feels like an oven in the parking lot, start the engine, turn on the air conditioning, and… nothing but hot air. Sweltering summer days might be perfect for watersports and other outdoor activities, but they can be downright miserable without working AC.
While most air conditioning problems should be addressed by a professional, still there are some things that you can do to investigate the problem with a non-working AC system. The reason behind the problem might even be a minor issue that you can resolve on your own. At the very least, you can arrive at a repair shop armed with enough information to allow for a quick and painless fix.
Initial inspection
If you are wondering why your car AC is not blowing cold air and you want to get to the bottom of the issue, you will need to think like a technician. The first step in solving your problem is to “verify the complaint”. Well, so far all you know is that the air coming from the vents in your car does not feel cold. That is a good first step.
Now, put on your “technician” hat and verify the problem. With the car running, switch the AC to the “on” position (the air conditioner will not work unless the engine is running). Select the “normal” or fresh air setting (rather than recirculated air) and make sure it is coming out of the dash vents. Turn the fan all the way up. Now, make sure that the light indicating the AC system is on is actually “on”.
If the light does not come on to indicate that the AC system is operating, there could be a number of causes. The simplest one that you can check yourself is the fuse. Using your vehicle owner’s manual for reference, locate the fuse for the AC system and check that it has not blown. Besides a blown fuse, other reasons might include a broken wire, faulty ground, or low refrigerant level.
If, on the other hand, the light is blinking, you could have something as simple as a worn serpentine belt or as severe as a bad AC compressor clutch. A weak ground or low refrigerant level could also cause the light to blink.
Once you have determined that the light is indeed on to tell you the system is operating, the next step in your investigation is to determine any related symptoms.
You know you have no cold air. Now, listen at a vent. Do you hear any strange noises coming from the vent? Feel the air from the vent. Is it slightly cooler than the surrounding air? Or is it the same or warmer? What about the amount of air coming out? Is it coming out forcefully or is it weak? And pay attention to the smell. Do you notice any foul odor coming from the vent?
Next, you want to analyze the symptoms and isolate the problem. For instance, if you hear a squealing or whining sound when the AC is on, you could check the serpentine drive belt for signs of wear (turn the engine off first!). Another place the sound could be coming from is the AC compressor. If the air feels warmer than the rest of the air in your car, look to see if the temperature setting is set to “warm”. It happens. If you smell a musty or other foul odor, check the cabin air filter that cleans the air entering the passenger compartment. It is usually a fairly simple procedure that can often be done at home.
Each of these potential problems – a bad fuse, improper setting, worn serpentine belt, or clogged filter – can prevent your air conditioner from working as it should. And each of them is something you can probably check on your own. Anything more will require that you have at least a basic understanding of how automotive air conditioning works.
How your AC works
To go any further with your investigation, it helps to understand the basics of auto AC. In a nutshell, your AC system is a closed loop of various components designed to channel refrigerant (often called “Freon”, although that is a trade name for an outdated refrigerant) through high- and low-pressure stages to create an evaporative cooling process. If all of the components are working as they should, you have cold air coming from the vents. A breakdown anywhere in the system and you do not.
First, the AC compressor, a mechanical pump, compresses the refrigerant – at this point in gaseous form – creating a hot, high-pressure gas. The compressor is activated by way of a clutch driven by the serpentine drive belt, the same one (on most vehicles) that drives the alternator and power steering pump. A worn belt can mean that the compressor clutch pulley does not spin fast enough to operate the system. A bad clutch means the compressor will not turn on. And a failing AC compressor means that the refrigerant will not move through the system.
From the compressor, the refrigerant moves to the condenser, a device similar to (and located in front of) your car’s radiator that keeps the engine cool so that it does not overheat. Inside the condenser, the refrigerant cools down as air passes through the fins of the condenser. When this happens, the refrigerant becomes a cold liquid and moves along to the evaporator located under the dash in the passenger compartment.
Inside the evaporator, the cold liquid “steals” the heat from the surrounding air and makes the aluminum fins of the evaporator very cold. A blower motor forces air past the cold evaporator and into the passenger compartment.
While it is obvious that this description is an oversimplification of the process, you can see that there are a lot of variables at play in your car’s AC system.
The main reasons that your air conditioner does not blow cold air revolve around a low refrigerant level (usually because of a leak), failing compressor, or faulty wiring, each of which require the help of a professional.
Sure, you can buy a DIY kit to add refrigerant on your own, but that is not a very good option. First of all, the type of refrigerant sold in those kits may not be the same thing that is in your car to begin with. Besides, your car calls for a specific amount, or weight, of refrigerant to operate properly. The refrigerant must be measured at a certain temperature when added as a gas, or at a particular weight when added as a liquid. Too little and the system will not work (or will be intermittent). Too much and you could burn up your compressor.
What you might be able to do is check that the condenser, located just behind the grill at the front of your vehicle, is not caked with debris preventing air from passing through. If it is, and if you can gain access, you can use a soft brush and a bit of air or water to clean away the debris. Just be careful not to damage the sensitive aluminum fins or passageways.
In summary, you can safely accomplish the following if your AC doesn’t blow cold air:
- Start your engine and turn on the A
- Verify that the indicator light is “on
- Check the temperature, sound, smell, and force of the air coming out of the dash ven
- Check the fus
- Inspect the serpentine drive belt with the engine of
- Inspect the wiring that leads to the AC compressor
Clean debris from the condenser
Other than those operations, you should leave the rest to a trained technician at a trusted repair shop. If you are able to correct a simple issue on your own but you notice that your AC system puts on a repeat performance, schedule an appointment to have the system inspected. Now that summer is on the doorstep, you probably should not wait until a problem gets worse.
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