Written by: Linda Chen
Last updated on: July 3rd, 2026
It happens every summer without fail. The temperature spikes across Greater Vancouver, you crank up your AC, and somewhere between Langley and Burnaby, thousands of air conditioners decide they’ve had enough.
Overheating is one of the most common reasons ACs break down during heat waves — and the frustrating part is that it rarely happens without warning. Your system almost always gives you signals before it shuts off completely. The problem is most people don’t know what to look for until they’re sweating through a Thursday night with no cold air coming out.
We put together this guide to help you catch the early signs and actually do something about it before a repair call turns into a full replacement conversation.
Why Do Air Conditioners Overheat in the First Place?
Your AC works by moving heat from inside your home to the outside. During an extended heat wave — the kind we’ve been seeing more often across Surrey, Delta, and Squamish in recent years — that outdoor unit is already working against scorching ambient temperatures. Throw in a dirty filter, a refrigerant issue, or restricted airflow, and the system starts running longer and harder than it was designed to.
The compressor, which is essentially the heart of your AC, is especially vulnerable. When it overheats, the system’s thermal protection kicks in and shuts the unit down. Sometimes it restarts after cooling off. Sometimes it doesn’t. And sometimes you end up with a burned-out compressor that’s costly to replace.
Knowing the warning signs early gives you options.
Sign #1: Your AC is Running Constantly But Not Cooling
If your air conditioner has been running for hours and your home still feels warm or stuffy, that’s not just annoying — it’s a red flag.
A properly functioning AC should cycle on and off as it maintains your set temperature. When it runs non-stop, it usually means the system is working overtime to keep up with demand it physically can’t meet. That sustained effort generates heat inside the unit itself, pushing the compressor closer to its thermal limit.
What to do: Check your thermostat first — make sure it’s set to “cool” and not “fan only.” Then check your air filter. A clogged filter is one of the most common causes of restricted airflow, and restricted airflow is one of the most common causes of overheating. If the filter looks grey and matted, replace it. If the system still won’t catch up after that, it’s time to call a technician.
Sign #2: The Circuit Breaker Keeps Tripping
Your AC tripping the breaker once during a heat wave can be a fluke. If it’s happening repeatedly, that’s your electrical panel telling you something is wrong.
When a compressor starts to overheat, it draws more current than usual to try to maintain performance. If the amperage climbs high enough, the breaker trips as a safety measure. Most homeowners reset the breaker and move on — but if it trips again within a few hours, resetting it again isn’t a fix. It’s just delaying a bigger problem.
Repeatedly forcing power to an overheating compressor can cause permanent damage to the motor windings, which is one of those repairs that often makes replacement the more economical choice.
What to do: Reset the breaker once. Give the unit 30 minutes to cool down before turning it back on. If it trips again, leave it off and call for service. This isn’t a DIY situation.
Sign #3: You Hear Strange Noises Coming From the Outdoor Unit
Air conditioners aren’t silent, but they do have a normal sound — a steady hum with the occasional click as the compressor cycles. When you start hearing grinding, clanking, rattling, or a high-pitched screech, something mechanical is struggling.
Grinding often points to worn motor bearings. Rattling can mean a loose component is vibrating against the housing. A high-pitched squeal sometimes indicates the fan belt (on older units) is slipping, or that refrigerant is escaping through a small leak — which also contributes to overheating because low refrigerant forces the compressor to work harder.
These noises tend to get worse during heat waves because everything is running longer and under more stress.
What to do: Turn off the unit and inspect the outdoor condenser for visible debris — leaves, twigs, or anything that might have gotten into the fan. Clear away any vegetation or objects within two feet of the unit. If the noise continues after a clean restart, you likely have a mechanical issue that needs professional diagnosis.
Sign #4: Warm Air or Weak Airflow From Your Vents
Put your hand up to a vent while the AC is running. You should feel a consistent flow of cool air. If what you’re feeling is lukewarm, barely moving, or coming out in uneven bursts, your system isn’t doing its job.
Weak airflow is often caused by a dirty evaporator coil, a failing blower motor, or ductwork issues. Warm air coming from the vents despite the AC running usually points to either a refrigerant problem or a compressor that’s already struggling.
Both scenarios lead to the same outcome: the unit has to run longer to compensate, generating more heat internally, and accelerating wear on components that are already under stress.
What to do: Replace your air filter if you haven’t recently. Check that all your supply vents are open and unobstructed by furniture or curtains. If airflow is still weak or air is still warm after those checks, the issue is likely inside the system — evaporator coil cleaning or a refrigerant check from a licensed HVAC technician is the next step.
Sign #5: The Unit Shuts Off on Its Own and Won’t Restart
This is the sign most people notice when it’s already too late to prevent a service call. Your AC was running fine, then it just… stopped. You try to turn it back on, nothing happens. Maybe it starts briefly and cuts out again.
This is almost always the thermal overload protection doing its job. Modern AC units are built with a safety switch that cuts power to the compressor when temperatures inside the unit get dangerously high. It’s designed to prevent catastrophic failure, but it also means your system detected a problem serious enough to shut itself down.
In some cases, the unit will restart on its own after 30 to 60 minutes once things cool down. That’s not a clean bill of health — it’s a borrowed hour.
What to do: Let the unit rest for at least 30 minutes in a shaded spot before trying to restart it. While it’s off, check the outdoor unit for blocked airflow — debris, overgrown plants, or anything pressing against the condenser fins. Check your filter. If the unit shuts itself off again after restarting, stop running it and call a technician. Continuing to force a unit that keeps tripping its own safety shutoff is the fastest way to turn a repair into a replacement.
How to Reduce the Risk of Overheating This Summer
A few things go a long way during heat waves:
Change your filter regularly. During heavy cooling season, once a month is reasonable for most homes. A clean filter is the single easiest thing you can do to protect your system.
Keep the outdoor unit clear. The condenser needs room to breathe. Keep grass, shrubs, and stored items at least two feet away on all sides. Hose down the condenser fins periodically to remove dust and debris — just make sure the unit is off before you do.
Don’t block your vents. Furniture pushed against supply vents restricts airflow and makes your system work harder than it needs to.
Use your thermostat strategically. Raising the set temperature by even two or three degrees reduces how hard the system has to work. Pre-cooling your home in the morning before the peak afternoon heat also helps.
Schedule a maintenance visit before summer peaks. An annual tune-up — coil cleaning, refrigerant check, electrical inspection — can catch issues before they become failures.
When to Call Aire Energy
If your AC is showing any of these signs during a heat wave, the team at Aire Energy is available 24/7 across the Greater Vancouver Area. We service Langley, Surrey, Delta, Coquitlam, Burnaby, Squamish, and surrounding communities.
Our licensed technicians work on all makes and models, carry the parts for the systems we service, and won’t leave you waiting. Same-day service is available, and if your repair cost makes more sense as a replacement, we’ll tell you honestly — and handle the rebate paperwork on qualifying new systems so you don’t have to.
Call us anytime at 1(855)-847-7892 or visit aireenergy.com to book a service call.
Don’t wait for the unit to shut down completely. A small fix today is almost always cheaper than an emergency replacement in the middle of August.
Aire Energy provides 24/7 HVAC installation and repair services across the Greater Vancouver Area, including Langley, Surrey, Delta, Coquitlam, Burnaby, and Squamish. We’re a trusted dealer for Lennox, Goodman, and Gree systems, and we assist homeowners with CleanBC and FortisBC rebate applications.
