Newer AC units are surprisingly quiet compared to some older models that sound like an airplane taking off. However, if you expect your air conditioner to operate silently, you might have unrealistic expectations.
As with any other piece of equipment, noise is pretty much normal. Nevertheless, unexpected sounds might be a cause for concern, especially if you start hearing your AC making hissing noises.
If you owned an HVAC system for a while, you’re probably aware that the troubleshooting process can be tricky. AC making hissing noises is no different, as multiple things could be causing an issue.
To help put your mind at ease, we put together a quick troubleshooting guide that will help you focus on the problem.
Time to dig in!
The cause of the hissing sound
Before troubleshooting, you should first pay some extra attention to the sound. Is your AC making hissing noises that stop after a few seconds? If the answer is yes, you have no reason to worry.
A short hissing sound is perfectly ok as it’s just the sound of the refrigerant gas in the expansion valve of your unit.
However, if the AC is making hissing noises that are persistent, it probably indicates a bigger problem, such as any of the following:
1. Refrigerant leaks
If you hear bubbling along with your AC making hissing noises, this is the number one indication of a refrigerant leak in your system. The hissing is refrigerant in gas form escaping through the leak. Since refrigerant is a toxic chemical, it poses a health and environmental risk.
If you want to be 100% sure that it’s a refrigerant leak you’re up against, you should look at some other signs.
For instance, things like ice formations anywhere on your unit or your vents blowing hot air are other common symptoms. Additionally, abnormally high energy bills are also one of the symptoms. Low refrigerant levels usually make your AC struggle to maintain a proper temperature, thus wasting more power.
Unfortunately, the remaining thing you should do now is shut off the power to the unit and call a professional HVAC technician to inspect your system.
Not only is the refrigerant highly poisonous, but you’ll also need specialized tools to locate a leak that could be pretty small for untrained eyes to see. Even if you somehow managed to do that, refilling the system with the proper amount of refrigerant and pressurizing is no easy task.
2. Leaky ducts
A telltale sign of leaky ducts is AC making hissing noises and a high-pitch squealing originating from the vents. Why this happens is quite simple – deteriorating air ducts can develop many small gaps, tears, or cracks, which allow the air to escape.
If you’re not sure if leaky ducts are behind your AC making hissing noises, other things could be a dead giveaway. For instance, if you have difficulties keeping your home at a comfortable temperature, your air ducts are probably leaking. Since air-conditioned air travels through the air ducts before reaching your rooms, that cool breezy air might escape into places like attics or walls if there are cracks.
Just as with refrigerant leaks, leaky air ducts will lead to high energy bills since your AC will start compensating for all the escaped air.
The question here is: can you fix this problem yourself?
If you want to pull your hair out in frustration, then maybe yes. In all seriousness, we cannot recommend it. Your entire ductwork system is concealed behind walls and ceilings, and you’d first have to inspect every duct in your home before you perform the duct sealing itself. If you appreciate your time, please call a professional.
3. Too much pressure inside the compressor
The compressor is a crucial part of the HVAC system. It’s located inside the outside unit and it’s the main component of the refrigerant circulation as it moves refrigerant through the system.
Since the compressor is pressurized, too much pressure can build up in the outside unit, which can lead to AC making hissing noises. In the worst-case scenario, the extra pressure can cause the compressor to malfunction, putting your unit out of service.
Additional symptoms of this problem may include a loud screeching sound that lasts over ten seconds after you power on the system. Moreover, if your AC turns on and off a lot more often than usual, there might be too much pressure inside the compressor.
Since you would require the right tools to properly fix this problem and the necessary experience to pressurize the system properly, this too is something that’s best left to the professionals.
4. Malfunctioning reversing valve
The final culprit behind the AC making hissing noises problem is for all our readers who have a heat pump (a unit which cools and heats the air). The reverse valve might be the cause.
This valve is a part of the heat pump and is responsible for switching the flow of refrigerant in the system, thus allowing it to heat and cool. However, if it malfunctions, it can cause a lot of problems.
A broken reversing valve can get stuck between the two modes, which not only causes the hissing sound but also causes subpar cooling. So if you notice your AC making hissing noises along with an inconsistent temperature and a high energy bill, it might be the reversing valve.
If you’re wondering whether you can fix this problem yourself, we’ll have to disappoint you for the fourth time today. A malfunctioning reversing valve is a serious issue that could point to several other problems with your AC. For instance, the valve itself might be burnt or oxidized, which could point to overheating.
Overheating is a serious problem that requires professional help.
Keeping your AC healthy
While AC making hissing noises can be pretty annoying, it’s a positive thing as it gives you a sign that something is wrong.
As an HVAC owner, your job is to keep a close eye on any weird behaviors your AC might exhibit and learn enough to be able to report them. But more importantly, it’s your job to keep your AC healthy by maintaining it regularly to minimize the chance of problems happening.
This includes cleaning your AC, ensuring it always has good airflow, and swapping out the air filters every few months.
While you shouldn’t attempt fixing these malfunctions yourself, it’s not a problem for experienced HVAC technicians. For all the bigger repairs, you need to call a professional to restore your AC to tip-top condition.
If you want a fast and cost-effective AC repair service available 24/7 in Florida, call Aztil AC at (888) 729-8452 or send an email to email@example.com, and we’ll get to fixing your AC making hissing noises right away.