Back to all

Your Vehicle's Hissy Fit (AC System)

December 11, 2022

When you hear hissing sounds coming from your vehicle, you might start thinking the worst.   One type of hissing coming from around your air conditioner may be a normal sound, or it could be a sign of serious trouble.

First - the normal sound.  When you turn off your vehicle, the refrigerant goes from its high-pressure side to the low-pressure side. Some of those noises are normal.  But when it hisses all the time, that's another story.

One cause could be that the refrigerant is leaking.  Air conditioners are fairly complex systems that involve various pumps, hoses, valves and motors.  When your air conditioner is cooling, the refrigerant changes from a gas to a liquid and back.  That refrigerant is under pressure, and there are many places it can leak from. 

A hissing sound can also be a failed valve in your air conditioner's compressor.  It is what controls the refrigerant's pressurization.  It's important to have this fixed fairly quickly after it develops a problem because when it isn't, that can lead to more extensive—and expensive—repairs.

If you hear screeching coming from your air conditioner at the same time you hear hissing, your compressor may be on its last legs. It could also be a defective clutch. 

Any time you hear a noise you haven't routinely heard before, bring your vehicle to us so a technician can check the various components and properly repair the problems.  Air conditioning systems are complex and are best handled by a professional with the right tools and equipment.  When your AC has a hissy fit, let us cool it off and you at the same time.  

Charlie's Fast Lube Sparta
10 Northtown Drive
Sparta, Illinois 62286
618-443-6112
http://www.charliesfastlubesparta.com

Need Service?

Request a Quote

More articles from Charlie's Fast Lube Sparta

No Fuel-ing! (Fuel Filter Replacement)

January 4, 2026

Your vehicle has a few filters you might be somewhat familiar with. Theres the oil filter that removes impurities from your engines oil, and a couple of different kinds of air filters that prevent contaminants from getting into the engine and the cabin. But you may not know that your vehicle als... More

Knowledge is Power (Battery Testing)

December 28, 2025

Its likely happened to you once or twice. You head to your vehicle, open the door, turn the key and lo and behold, your battery is dead. Now youre stranded, may have to get a jump or a tow, and youll definitely be late for wherever you were headed. While your vehicle may sometimes give you warni... More

Trickle Down Technology

December 21, 2025

Recently, Nissan introduced the latest version of its Leaf, the company's electric car. It has many new features, including something called e-Pedal. It allows the driver to let up on the accelerator and, unlike a gasoline engine car, the Leaf doesn't just slowly lose speed; letting off the throt... More