Has the air conditioner in your automobile recently failed you?
There are not many things worse than expecting a chilly breeze but instead being met with a blast of searing heat.
If you’re scouring the web for answers to “why is my car AC blowing tepid air?” then you’ve come to the right place.
The most common cause of an AC system blowing warm air is a lack of refrigerant, though you may also have a problem with your condenser. Other possibilities include a defective compressor, broken cooling fans, or an issue in your electrical system.
Fortunately, in this thorough guide, I will review each of these vehicle AC problems in detail.
But first, I will explore how precisely the AC system functions for a car to help you better understand why it is having problems.
Let us commence!
Table of ContentsShow
Your Car’s AC System Explained
Compressor
The compressor takes refrigerant that is at low pressure and low temperature, in gas form, and compresses it into gas that is at increased pressure and intense temperature as its name suggests.
Condenser
The condenser acts as a mini radiator. It receives the elevated-temperature, high-pressure gas from the compressor and radiates the heat out of it. When this happens, the refrigerant condenses, transforming it into a high-pressure, cool liquid.
There’s also a pair of cooling fans that blow over the condenser. This removes much of the heat from the refrigerant while it’s in the lines.
Receiver/Dryer
The receiver/dryer is in charge of removing moisture from the refrigerant now that it’s in a fluid state. It does this by filtering it through desiccants, a moisture-absorbing material.
If you ever discovered a small pouch in a medication bottle or new shoes, it’s essentially the same substance.
The reason moisture needs to be removed from the refrigerant is to keep it from freezing, which can hinder the expansion valve. Water has a freezing point of -32 degrees. Refrigerant, on the other hand, has a freezing point of as low as -200 degrees.
Expansion Valve/Orifice Tube
An expansion valve essentially controls how much coolant passes through the system, similar to the nozzle on a hose. As it passes through the expansion valve, it expands, decreasing pressure and temperature simultaneously.
Not only that, but this process also converts it back into a gaseous state, except this time, it’s icy, low-pressure.
Some configurations have an orifice tube rather than an expansion valve.
They both work similarly, except that the former can regulate the size of its aperture based on the temperature in the evaporator. In this type of system, the receiver/dryer is replaced with an accumulator, which also operates comparably.
Evaporator
The evaporator also functions like a radiator, with tubes inside that the refrigerant passes through. While in these pipes, the heat is absorbed and sent outwards, reducing it to about 32 degrees Fahrenheit.
The peculiar thing about coolant is that unlike water, which freezes at 32 degrees, it boils. This not only lowers the temperature further but also causes it to evaporate, turning it back into a gaseous substance.
A fan then blows over the evaporator, pushing icy air-conditioned air into your cabin. The coolant returns to the compressor as a low-temperature, low-pressure vapor, starting the process over again.
5 Reasons Your AC Is Blowing Hot Air And How To Fix Them
Your Car Is Leaking Refrigerant
Since refrigerant is recycled over and over, the only reason you should ever have to recharge it is if there’s a leak somewhere in the system. The initial indication of a leak is if your AC starts blowing lukewarm air.
Regrettably, identifying precisely where the leak is coming from can be challenging. Why? Because once it reaches an area of low pressure, such as a leak, it returns to a gaseous state.
There are two options to manage an AC leak.
The first is to take it to a shop, which will locate the leak and repair any damage or replace any degraded parts. Depending on the severity of the issue, this can run anywhere between $225-$1600. If the leak stems from a worn hose, expect it to be less than if the compressor needs replacing.
The second option is to use an AC leak sealer, though keep in mind that these products are designed for minor leaks.
There are two types of leak sealers. The first kind conditions the seals, causing them to expand. The second kind flows through the system until it reaches a leak and forms a rigid material to help block it.
You can pick up a canister of either for between $25-$50. Most feature a nozzle that connects directly to the high-pressure port. However, be sure to follow the product instructions step by step.
The Condenser Is Malfunctioning
If you remember from earlier, the condenser is in charge of removing heat from the refrigerant and then expelling it outward. If, for any reason, it’s faulty, your car AC will blow tepid.
Since the condenser rests behind the front grille, it’s possible that road debris has caused a blockage or pierced one of the interior tubes.
While removing a blockage is possible, repairs are usually not, meaning you’ll need to replace it. Replacing a condenser costs anywhere from $450 to $950, depending on the make and model of your car.
Issues In The Electrical System
If your air conditioning is releasing warm air, the last thing you want is for it to stem from an electrical problem. Why? Because finding the location of the issue can be arduous as numerous wires are not visible without taking apart the complex system.
Many of the AC components need electricity to function, and if they aren’t receiving any, your AC system will likely blow tepid.
While you may be able to mend any frayed or damaged wires with electrical tape, your best option is to take it to an experienced professional.
Problems With The Cooling Fans
As discussed earlier, the condenser also has a pair of cooling fans that help reduce the heat of the refrigerant while it’s in the lines. If these are impaired or malfunctioning, the AC system will not operate as intended.
There are several reasons they might cease functioning, such as a fuse blowing or a problem in the electrical system. They may also become damaged from road debris due to being close to the front of the car. In this instance, replacement is the sole option. Expect to spend between $300-$500 to replace them.
The Compressor Is Faulty
It all starts in the compressor, and as you might have deduced, if it’s not operating correctly, neither will the rest of the system. Why? Because the compressor is what gets the refrigerant moving in the original place.
Why do AC compressors go even defective?
One of the most widespread causes is lack of use. Whenever you crank your AC after extended periods without use, it can shock the system, which can cause it to wear faster than normal.
For this reason, it is always a sensible idea to run it for about 15-minutes every few weeks.
There are a lot of shifting components in the compressor, making it almost better to replace it than repair it.
Regrettably, you’re still looking at a replacement cost of between $500 to $700. Luckily, you can extend the life of your AC compressor by using it more frequently.
Why Does Your Car AC Blow Hot Air?
That is because something internally is defective and needs your attention.
Thankfully, if you have made it this far, you should have a much clearer idea as to the cause. The longer you wait to resolve the issue, the more likely it is to lead to something more serious.
Regardless, can you really survive in a sweltering climate without a functioning AC system? It’s not worth it.
