Why your air conditioner got louder, and what it is probably costing you

It is August, the unit outside has been running most of the day, and it sounds different than it did last summer. A bit louder. Maybe a rattle that was not there before.

Most people put up with it, or assume the system is on its way out. Usually it is neither. A louder unit is normally telling you one of two things, and the difference between them matters.

Something has worked loose. Annoying, cheap to fix, tends to get worse.

The system is working harder than it should be. That one is already showing up on your hydro bill, and the noise is just the part you happened to notice.

The expensive version

ENERGY STAR's guidance is blunt about this. Dirty coils reduce a system's ability to cool your home, which makes it run longer, increases energy costs, and reduces the life of the equipment. Refrigerant works the same way. Too much or too little makes the system less efficient, again driving up costs and shortening equipment life.

Notice that none of that describes a sound. It describes runtime.

A system that used to cool the house and shut off is now running through the whole afternoon. It might not be a single decibel louder at any given moment. You are simply hearing it far more of the time, and paying for every minute of it.

That is why "it seems louder this year" is worth taking seriously. It is often the first symptom you notice of something that has been quietly costing you for a while.

The cheap version

The other cause is mechanical wear, and the City of Vancouver spells this one out in its own guidance for heat pumps and outdoor mechanical equipment. Noise from fans and motors increases over time without periodic maintenance, because parts like bearings wear and screws work loose enough to rattle.

Same guidance also tells owners to keep the coils clear of dirt and debris and change the filter regularly, which is the overlap between the cheap problem and the expensive one.

How to tell which you have

• A rattle or buzz that comes and goes. Something loose. A panel, a fastener, a fan guard.
• A steady low drone that has always been there. That is the compressor. Normal.
• Running noticeably longer than last year. This is the one that costs you. Airflow, a dirty coil, or refrigerant.
• Grinding or screeching. Not a wait-and-see. Shut it off and call someone.

Where the bylaw comes in

Worth knowing if a neighbour has said something, or if you are worried one might.

Vancouver has regulated this since 1989. The Noise Control By-law sets residential limits of 55 dB between 7am and 10pm, and 45 dB overnight. The part most people miss is that those are measured at the property line, not at the unit. Two identical systems on two identical houses can land on opposite sides of the limit purely because of where they sit and what stands between them and the neighbour.

The City's advice for placement is to keep the unit as far from the property line as possible and to favour the front or rear yard over the side yard, using fences, hedges, or landscaping as barriers. Their rule of thumb is that if you can see it, you can usually hear it.

On plenty of Vancouver lots, the side yard is the only place a condenser will physically fit. That is a real constraint rather than bad work. When it is the only option, what matters is keeping the unit away from the neighbour's windows, mounting it on a solid base like a concrete pad with rubber dampeners to control vibration, and using whatever barrier already exists.

Maintenance matters here too. A unit that has been serviced is quieter than one that has not, which sometimes resolves a neighbour issue without moving anything.

The short version

Louder is a symptom, not a diagnosis. Something loose is a nuisance. A system running longer than it should is a bill. Neither one is usually a reason to replace anything.

One note on picking who does the work: in British Columbia, purchasing and handling refrigerant legally requires certification through the Environment Canada and HRAI program. Anyone topping up a system without that, or without finding the leak that caused the low charge, is not doing you a favour. Refrigerant is not consumed like fuel. If it is low, it went somewhere.

Air Comfort Systems installs and services central air, ductless mini splits, and heat pumps across Metro Vancouver, with Red Seal certified technicians on every job.