What Causes the AC System to Leak?

Your car’s air conditioner is responsible for keeping the interior cool and comfortable on hot days. However, in order to do that, you need the right level of refrigerant in the system. If your refrigerant is low, the air conditioner may blow warm or hot air. A special switch is designed to sense when there isn’t enough pressure (or when pressure is too high) and disengage the AC compressor clutch, which operates the compressor to pressurize the system.

Causes of low refrigerant

There are a number of potential causes for low refrigerant in your car’s AC system. Some refrigerant is lost naturally over time. It takes years, though, so if your car isn’t that old or the system has been recharged recently and is now blowing warm air again, chances are good that you’ve got a leak somewhere.

There are two causes of AC system leaks – age and moisture. While much of your air conditioning system is made of metal, including the high pressure lines, rubber is still used throughout. You have rubber O-rings, grommets, lines and more. The problem here is that rubber degrades over time and with exposure to heat and moisture. As that wear accelerates, the affected part will fail. Something as simple as a degrading O-ring can cause you to loose refrigerant surprisingly quickly.

Other sources for a leak include:

  • Failed Seal
  • Failed Hose

That’s not the end of it, though. If you have a leak in your air conditioning system, it’s possible that moisture has entered the lines. Moisture in an automotive AC system is very bad. It mixes with the refrigerant left over and creates a type of acid. Once your system is contaminated with moisture, it’s very possible that other components will be affected and require replacement. This can include:

  • The receiver/dryer
  • Accumulator

Detecting the leak in a timely manner is vital. If you wait too long from the initial point of AC malfunction, moisture will enter the system. Locating the source of a leak depends on the type of system you have. Some are pre-injected with UV dye, while others will have to be charged with dye. In both cases, a black light held over the engine will show where the refrigerant is leaking.


Next Step

Schedule AC is not working Inspection

The most popular service booked by readers of this article is AC is not working Inspection. Once the problem has been diagnosed, you will be provided with an upfront quote for the recommended fix and receive $20.00 off as a credit towards the repair. YourMechanic’s technicians bring the dealership to you by performing this job at your home or office 7-days a week between 7AM-9PM. We currently cover over 2,000 cities and have 100k+ 5-star reviews... LEARN MORE

SEE PRICING & SCHEDULING

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Recent AC is not working Inspection reviews

Excellent Rating

(1,163)

Rating Summary
1,098
29
7
11
18
1,098
29
7
11
18

Greg

22 years of experience
333 reviews
Greg
22 years of experience
Toyota Corolla L4-1.8L - AC is not working - San Tan Valley, Arizona
Greg was very knowledgeable and shared all of the information and recommendations for my vehicle. He is personable and does a great job. Thank you Greg!
Nissan Rogue - AC is not working - Surprise, Arizona
Very happy Greg was able to come back, since he originally installed my compressor. He's honest, forthcoming, and explains exactly what he checks.and exactly what he does! I'm pleased yet again with my appointment! AND I have a/c again! Thanks so much!

John

27 years of experience
1019 reviews
John
27 years of experience
Kia Forte L4-2.0L - AC is not working - Houston, Texas
I really like this guy. He was direct, straight to the point & fairly honest about other things I already knew what was wrong with my car. I honestly felt like I could actually trust and believe In the guys integrity.
Nissan Rogue Sport - AC is not working - League City, Texas
Quick, efficient, detailed, professional. Everything you’re looking for in a mechanic! HIGHLY recommend him. Thank you so much!!

Benji

22 years of experience
277 reviews
Benji
22 years of experience
Honda Accord L4-2.4L - AC is not working - Phoenix, Arizona
Benji was running behind on his appointments. He called to give me very early notice to plan accordingly since he was 20 minutes behind. He's super friendly, knowledgeable, and a pleasure to work it. I would work with Benji again for my auto needs and recommend him to people I know.
GMC Yukon - AC is not working - Chandler, Arizona
On time, friendly, and professional. Gave thorough explanation of findings and answered all my questions - I would not hesitate in recommending Benji to anyone.

Peter

25 years of experience
514 reviews
Peter
25 years of experience
Toyota Matrix L4-1.8L - AC is not working - Los Angeles, California
Peter was incredibly detailed and was able to diagnose and fix my AC issue. As a new car owner, 10/10 I would hire Peter again to help diagnose and fix the issues on my Toyota. Thank you!!!
Ford Taurus - AC is not working - Granada Hills, California
Great experience! Peter lives close by and contact me to see if he could come by a day early at the end of his day. He made the repair, gave me instructions on what to look for in the future and all took 30 minutes.

Need Help With Your Car?

Our certified mobile mechanics make house calls in over 2,000 U.S. cities. Fast, free online quotes for your car repair.

GET A QUOTE

Related articles

How to Replace an AC Condenser
The AC condenser malfunctions if the air conditioning system has clogged passages or leaks, or if the condenser electric fans stop working.
How to Replace an AC Accumulator
The accumulator in the air conditioning system is faulty if there is rattling inside of it or there is a moldy smell emitting from the AC system.
How to Replace a Car Air Conditioning (AC) Low Pressure Hose
Car air conditioning (AC) low pressure hoses carry refrigerant back into the compressor to keep providing cold air in a closed loop system.

Related questions

What climate control elements can be controlled from the touchscreen?
If your Fusion has the touchscreen navigation system installed, then it’s tied into your Automatic Climate Control system as well. You’ll find that some of the physical controls on the HVAC system are duplicated on the touchscreen (that way, if...
A/c blowing cold air intermittently with warm air
Hello. If the system continually blows hot and then cold, this is typically caused by a failing blend door actuator. If it fails, it can allow the temperature door to not hold the right position. It can also be caused...
Engine is vibrating at drive condition while AC is on though compressor, condenser, chamber changed.
Check the vehicles engine mounts. A failed engine mount (https://www.yourmechanic.com/services/engine-mount-replacement) may cause extra vibrations from the engine to make their way through the car and become very noticeable. Check your service history as well to be sure your maintenance (https://www.yourmechanic.com/scheduled-maintenance)...

How can we help?

Our service team is available 7 days a week, Monday - Friday from 6 AM to 5 PM PST, Saturday - Sunday 7 AM - 4 PM PST.

1 (855) 347-2779 · hi@yourmechanic.com