5 Reasons Your Car AC System Blows Warm Air (updated)

Have you ever cursed to yourself, “Why does my car ac blow warm air?”
You know that feeling when it’s boiling hot outside and you can’t wait to get into your car and blast the A/C unit? You’re just itching to be surrounded by all that amazing coolness so that you can feel like yourself again. There’s nothing quite like it, right? Then you get in, close the car door behind you, turn the A/C on and it blows hot air! You are a rare breed if you don’t Hulk out right there on the spot.

So, what could be behind the disaster that has befallen you? If you have been neglecting your car a bit before the summer’s arrival (read 8 spring care tips for your car), these 5 reasons might help you understand why your car A/C system blows warm air now.

1. Compressor is Not Engaging

The compressor is the most important component in a vehicle’s air conditioning system since that is where the car air is actually being cooled down. Its job is to pressurize and circulate the refrigerant through several stages and thus remove the heat from the car cabin. It is like a heart with two valves – and just as important to your air-con system as our heart is to your body. Having that in mind, it should come as no surprise that the compressor is highly susceptible to wearing out over time. Also, its complex build makes it difficult to determine both the exact part which is malfunctioning as well as for what reason. If, after you have started the A/C, the compressor doesn’t engage, the most probable culprits could be the compressor clutch, refrigerant level or even compressor as a whole. When this happens, it is simply not sucking in the Freon gas as well as it should. This is not something you should try to fix by yourself, unless, of course, you are a mechanic in your own right.

2. Refrigerant is Leaking

When the refrigerant isn’t pressurized in the compressor, it turns into gas. Now, you might think that this state allows it to disappear from your vehicle, as well as that should be a normal occurrence. However, since it circulates within the sealed A/C system, it is supposed to always remain at the same level and doesn’t need regular top-ups. So, should you notice the decrease in the refrigerant level, you are most certainly dealing with a leak.

Having in mind that your A/C system works in harsh conditions (very low temperatures in the winter and quite high in the summer), its parts aren’t immune to wear and tear. Such extremes in temperatures affect both metal and rubber parts which tend to become brittle and crack after several years of working hard. Those cracks then become tiny leak points through which the refrigerant can escape. When enough of it finds its way out, the system will become incapable of cooling the air efficiently, and you will slowly start noticing the change. While the good news is that it doesn’t happen overnight, the bad news is it’s not a simple fix. Since the refrigerant is invisible once it exits the system, don’t hope to see it leaking any more than that you can fix it on your own.

Identifying the source of the leak is difficult because once it reaches an area of low pressure it returns to a gaseous state.

There are two ways to take care of a leak. The first (and more advisable) option is to take it to a repair shop. They will locate the leak and then repair or replace any worn parts.

Your second option is to use an AC leak sealer. Bear in mind that these products are meant for small leaks only.
The one type of leak sealer conditions the seals, causing them to swell. The other flows through the system until it finds a leak, and then it creates a solid substance to block it. This can save you a lot of money but just be sure you follow the step-by-step instructions.

3. Condenser is Blocked or Broken

The condenser is there to cool off the hot refrigerant back to ambient temperature once it passes through the compressor. As it is located at the front end of the vehicle, it uses the air the car travels through to accomplish the goal. Otherwise, the hot refrigerant will just come back around, and your A/C unit will blow hot air in your face.

However, the condenser’s position is somewhat problematic, because it allows for road dirt, debris and even garbage to get stuck in it. This kind of blockage will make it difficult or even impossible for the cool air to come through to the refrigerant and lower its temperature. Therefore, it would do you good to check out the situation and remove what you can. What’s more, bigger and rougher objects like sticks and rocks can even perforate the condenser and then you’ll have an even more serious problem on your hands! If the hole is large enough that you can see it with the naked eye, then you must turn to professionals for help.

Removing blockages is possible, but repairs are generally not. You will likely have to replace it. Replacing a condenser costs in the hundreds of dollars depending on the make and model of your car.

4. Electrical System is Malfunctioning

Seeing as practically every car system is commanded by means of electronics, this is also something that might give you a headache if you find your A/C system is working poorly. All the fuses, switches, relays, and wires are interconnected to carry power to the A/C unit and operate safely as long as the operating conditions are normal. Furthermore, the electrical system is designed to shut down in case one of the components is malfunctioning to prevent electrical fires in the vehicle or the A/C system stop working altogether. Even though most of the air conditioning problems can be traced back to electrical malfunctions, they are not so easy to diagnose and isolate, so you should leave that to your mechanic.

5. Blend Door is Not Closing

The blend air door is a small hatch inside the ventilation system which allows you to choose whether you want the HVAC system to heat up or cool down the inside of your car. If you turn the cooling feature on and all that comes out is warm air, then it uses the heat from the engine instead of drawing in cool air. Thus, the blend door is stuck, and you are in desperate need of a mechanic to solve this problem for you since it cannot be reached so easily.

Even though these are not the only problems you might come across when the temperature becomes too high for your pleasure in the car, they are the most common ones. They could not only make your life living hell on the road, but also turn driving into a dangerous affair. If your attention is drawn to how uncomfortable you are feeling while driving, you are not a safe driver and are thus risking the lives of all those in the car with you as well as around you.

Do you know the danger of turning on the A/C after starting the engine? Most car manuals will tell you to open windows before starting up the AC. This is because the car accumulates toxic benzene while it is parked and the air con will pump that into the cabin before the cool air comes through. This is known to be carcinogenic!

Most air conditioning malfunctions tend to be rather complicated to repair, so unless you have experience or expertise in this field, you should take your car to an auto repair shop for these problems. Part of the reason that it is not advisable to try and repair air con units yourself is that there are many moving parts in the machinery and once you start taking things apart, more problems could arise.
Summer is around the corner, and you do not want a nasty surprise on the first hot day of the year. Check the air conditioning now and perhaps have it serviced before disaster strikes, so you can enjoy a long, hot summer in your cool car.

Should you notice your car A/C blows warm air, don’t compromise your safety and that of your loved ones. Come to our repair shops in Hamilton and let our licensed mechanics put your car troubles behind you!