Last Updated on April 4, 2024
Summer time is when we all want to be able to turn on our ACs and enjoy a cool car. But what do you do if your AC is blowing out hot air? Many car owners face this problem every summer. The most common cause of an AC system blowing hot air is due to a low level of refrigerant. Because the AC system relies on refrigerant to convert warm outside air into cooled air, not enough of it will cause the system to push the warm air into the cabin. Simply put, your car’s AC system cannot function correctly without proper levels of refrigerant.
However, in some cases the warm air may be the result of a broken condenser, compressor or an issue with your electrical system. But don’t worry, we’re here to help. In this post, we’ll explain why your AC might be blowing hot air and what you can do to fix the problem.
But before we jump into this, it’s good to know that your vehicle’s AC system consists of five main components:
- Compressor
- Condenser
- Receiver/Dryer
- Thermal Expansion Valve/Orifice Tube
- Evaporator
With that out of the way–let’s jump right into reasons for that AC blowing hot air.
Your Car is Leaking Refrigerant
When you think about something leaking from your car, the first thing that comes to mind is a puddle of liquid under it. But not so with refrigerant! This is because refrigerant evaporates instantly when it’s no longer under pressure and cycling through the AC system. The first sign to look for when you have a leak is reduced cooling of the air. The reduction of cooling eventually leads to total loss of cool air.
How do you find the leak? Well, it’s not easy because once the refrigerant leaks from the system it evaporates. You really only have two options to fix an AC leak.
Your first option is using an AC leak sealer. If you just started noticing the AC blowing air that isn’t cold, then trying a AC leak sealer might be the solution for you. For as little as $35-$55 dollars a can, AC leak sealer works by recharging the refrigerant and lubricating the seals. When the seals are lubricated, they expand and seal off the system from leaks.
Additionally, most leak sealer contains a red or blue dye to help identify leaks in the system. So, if the leak sealer doesn’t fix your AC woes, then at the very least a mechanic will easily be able to identify the leak in the system by looking for the dye.
For the cost, AC leak sealer is great solution but keep in mind it’s meant for smaller leaks.
If you tried the leak sealer and it didn’t fix the AC blowing hot air problem, then it’s time to make a visit to a repair shop that specializes in AC repair. Using special equipment, a mechanic will locate the leak and repair any damage or replace parts to get your AC system blowing cool air again.
Your Condenser Broken
The condenser is an important part of the AC system. It’s sole job is to remove the heat from the refrigerant as it cycles through the system. On most cars it’s located right behind the front grill, exposing it to as much outside air as possible. However, its front location makes it prone to road debris. Especially if you drive a lot of highway miles.
It’s possible that road debris have either caused an obstruction or penetrated one of the condensers lines. This results in a loss of refrigerant and the ability to shed heat, resulting in the AC blowing hot air.
A mechanic might be able remove the obstruction, but repairs usually aren’t possible so you’ll just have to buy new condenser. Costs range from $475 to $975 depending on your car make and model.
You Have an Issue with the Electrical System
The issue of your AC blowing hot air might simply come down to an electrical problem. But, what causes electrical problems for your car’s air conditioning? You might think it is just one thing, but in reality there are several. These could include any number of problems like a failed relay or fuse; or a loose or damaged wire.
However, the most common cause of AC problems from electrical issues is a bad relay or fuse. Relays and fuses can short out and cause the AC to stop working. But the good news is that relays and fuses are cheap and can easily be replaced. Here’s a great video on how to diagnose an AC system for failed relay or fuse.
If you prefer not to get your hands into the electrical components of the car, then make a trip to your local mechanic. They will be able to easily check your relays and fuses for you.
Your AC Compressor is Malfunctioning
The compressor is what makes your car’s air conditioner work. It circulates refrigerant through the system, and without it you wouldn’t have any AC at all! The most common cause of an AC compressor going bad is simply lack of use. When you turn on your air conditioner after a long period without using it, this can shock the system and wear out the unit faster than usual.
Good news is, it’s not hard to identify symptoms of a bad AC compressor in your car. The first sign of trouble is usually when you hear strange noises from your air conditioner. Listen for a grinding or whining noise when the AC is turned on. These noises are an indication the internal components of the compressor are going bad.
The AC compressor is a complicated machine, which often makes it difficult to fix. For that reason, mechanics will recommend replacing the failing compressor with a new unit. The average cost for AC compressor replacement is between $812 and $1,041.
A Little Preventative Maintenance Will Keep You Cool in the Summer
AC problems can be frustrating and expensive, but they can also be avoided by being proactive. During the winter months, turn on and run the AC for 15 minutes. This will keep all components of the AC system in good working order.
Final Thoughts
If you’re experiencing any of the symptoms we listed, it’s important to take your car in for a check-up as soon as possible. Unlike many of the components in today’s cars, there aren’t any warning lights that will alert you to problems with your air conditioning system. The longer you wait to resolve the issue, the more likely it is to lead to something more severe.
Have you ever had issues with your AC system? Let us know in the comments below.
Managing Editor
Christopher is an automotive technical writer. When he’s not at the local autocross event, he can often be found working on one of his cars. Specializes in automotive class action law, industry trends, and automotive maintenance. Email me direct, or learn more about us
