I’ve been working on cooling systems in Calgary for about 15 years, and I can tell you the same story keeps repeating. You book a visit because the house won’t cool like it used to, and you’re half-expecting some mysterious failure. Then we pop the panels and it’s something plain. A filter jammed in backwards. A coil that’s basically wearing a sweater of dust. A disconnect that’s been getting a bit too warm for a bit too long. If you’re just trying to understand what a proper maintenance visit looks like, sunday air conditioning is the page I’d point you to first.

A good service visit is less about “spraying and praying” and more about checking the stuff that actually wears out or drifts. We look at airflow and static pressure because a lot of cooling complaints are really duct or filter problems wearing an AC costume. We check the outdoor fan motor, the capacitor, and the contactor because those are common weak links and they usually give you warning signs if you know where to look. I’ve also seen plenty of units starving for air because someone stacked patio cushions right up against the outdoor unit. Looks tidy. Runs awful. You’d be surprised how often that’s the whole problem. Well, usually anyway.

And sometimes it’s not maintenance at all, it’s damage or a part that’s actually failed. When a compressor starts sounding wrong, or the coil is leaking, or the breaker keeps tripping, you stop talking about upkeep and you start talking about getting the thing running safely again. If you’re already past the “it’s a bit weak” stage and into “it’s not working,” this is where repair air conditioning comes into the picture, because at that point you need troubleshooting, not a quick once-over.

In the next sections I’ll walk you through the usual steps we do on a maintenance visit, the checks that actually matter, and the little red flags I’ve learned not to ignore. Not because it’s fancy, but because it saves you from that first hot weekend where everything quits at 4:55 p.m. on a Friday. I’ve been on those calls. You don’t want that call.

Thermostat calibration and system start-up checks: temperatures, airflow, and cycling behavior

The thermostat is the part you touch, so it gets blamed for everything. Sometimes it deserves it. During a seasonal check, I compare the thermostat reading to an accurate thermometer right at the return grille, and I also check how the thermostat is mounted and where it sits. If it is in direct sun, above a lamp, or getting a cold draft off a stairwell, it can “think” the house is warmer or cooler than it really is and you end up chasing comfort all day.

Calibration is not just a number on the screen, either. I watch how it stages and how it calls for cooling, then I confirm the indoor fan response at the furnace or air handler. If you want a sense of how long troubleshooting like this can take once things get weird, this page lays it out pretty well: How long should an AC repair take?. A misreading sensor is fast. A control issue that only happens every third cycle is not.

On start-up, I do temperature checks the plain way. Supply air temperature, return air temperature, and the temperature drop across the indoor coil once things settle. I give it a bit of time because the first minute or two can lie to you, especially if the system has been off all night. Big red flags are a tiny temperature drop (often airflow or charge related) or a drop that is huge but the house still feels clammy, which can point to airflow being choked down somewhere.

Airflow is the sneaky one because you cannot “see” it, you just feel a room that never gets comfortable. I check the filter condition, blower settings, and the static pressure if I have reason to. I have also opened enough returns to find a kid’s sock or a pet toy sitting right where it should not be. Sounds funny until you are the one paying for a service call because the basement bedroom is getting zero air.

Cycling behaviour tells a story if you actually watch it. Short cycling can be oversizing, a thermostat location problem, a safety opening, or a low airflow freeze-up that starts and stops the whole thing. Long run times can be normal on hot days in Calgary, but if it never seems to catch up and the outdoor unit is hot to the touch, I start checking coils, fan operation, and refrigerant metering. Most of the time, at least, the system is trying to do its job, it is just being asked to do it with one hand tied behind its back.

If you are comparing service options, I will be blunt: the good outfits spend time on these start-up checks because that is where you catch problems before you lose a weekend to a breakdown. If you are searching for air conditioning maintenance shops near me, ask whether they actually measure temperatures and watch cycling, or if they just “look it over” and head out. You want the boring numbers written down, because the boring numbers keep you comfortable.

Indoor unit service: filter shape, blower wheel wash-down, coil check, and drain line flush

The indoor section is where I see most of the “small stuff” that turns into big nuisance calls. Dust, pet hair, drywall powder after a reno, you name it. You can have a shiny outdoor section and still get weak airflow or a sour smell because the inside half is plugged up. This part of a regular visit is where we look at the things you live with day to day, not just the stuff out back.

First is the filter. Not just “is there a filter” but the condition and the fit. I’ve pulled filters that are bowed in the middle from being sucked in, and then air just sneaks around the edges and coats the coil anyway. If it’s a 1-inch filter, sometimes people buy the cheapest pack and it collapses. If it’s a media cabinet, the door doesn’t always latch right after someone checks it, so it bypasses. I’ll point out the right size, the right direction, and whether you’re changing it often enough for your house, because two dogs and a basement gym is a different story than a condo with one person.

Then we get into the blower wheel. This is the fan that actually moves the air through your ductwork, and it doesn’t take much buildup before the blades start looking fuzzy and the airflow drops. It also throws the balance off a bit, so you hear a hum or a faint vibration and you think the motor is failing. Sometimes it is, but I’ve cleaned wheels that were so caked the motor was working way harder than it should. Cleaning it is messy, a bit awkward, and absolutely worth doing if it’s dirty, because you feel the difference at the vents.

The evaporator coil inspection is next, and I’ll be honest, you don’t always know it’s dirty until you see it with a light and a mirror. A matted coil acts like a blanket, so the refrigerant can’t absorb heat properly, and you start getting longer run times, lukewarm supply air, or icing. I look for bent fins, oil staining that can hint at a leak, and any signs the pan underneath has been overflowing. If you want the bigger picture of routine care, our page on air condition maintenances lays out how we approach the whole system, but the coil check is one of those steps that catches problems early.

And yeah, the condensate drain line. Honestly, the number of times I’ve seen a system shut itself off because that line is plugged with algae is ridiculous. We flush it, clear the trap, and make sure it actually drains where it’s supposed to. If there’s a safety switch in the pan, we test it too, because that’s the thing that saves you from water on the floor. People ignore drains because they’re just plastic pipe. Until they aren’t “just” anything.

Indoor task	What I’m checking or doing	Common signs at home
Filter condition	Correct size, tight seal, clean media, no collapse or bowing	Dusty rooms, weak airflow, whistling at return grille
Blower wheel cleaning	Remove buildup on blades, check for wobble, confirm smooth spin	Noisy fan, uneven airflow, higher power use
Evaporator coil inspection	Check fin pack for dirt, icing marks, oil staining, pan condition	Long runtimes, stale odour, poor cooling, ice on lines
Condensate drain flushing	Clear slime, flush trap, verify steady drainage and safety switch operation	Musty smell, water near furnace, random shutoffs

Q&A:

What does a professional AC tune-up typically include?

A typical air conditioning tune-up covers both safety checks and performance checks. A technician will usually inspect the indoor and outdoor units, confirm the thermostat is responding correctly, and check the air filter condition. They’ll clean debris from the outdoor coil area, inspect the indoor coil and drain system, and look over electrical components (contacts, wiring condition, capacitor readings, and the disconnect). They also measure airflow and system temperatures to see whether the unit is moving enough air and cooling properly. Many tune-ups finish with checking refrigerant pressures and temperature readings, verifying the condensate drain is flowing, and recording results so changes can be tracked at future visits.

Do you actually clean the coils during a tune-up, or is it just a quick look?

Most tune-ups include at least basic cleaning, but the level depends on access and how dirty the system is. The outdoor condenser coil often gets a rinse and removal of leaves, grass clippings, and buildup that blocks airflow. The indoor evaporator coil is harder to access; if it’s only lightly dusty, the tech may inspect it and clean reachable surfaces, but a heavily matted coil may require a separate coil-cleaning service (more time, more disassembly). A good tune-up should still include checking coil condition and measuring temperature change across the coil, because a dirty coil can cause poor cooling, longer run times, and higher energy use.

Will a tune-up include checking refrigerant, and can you tell if I have a leak?

Yes—refrigerant checks are usually part of the visit, but “checking” doesn’t always mean “adding.” The technician will take pressure and temperature readings and compare them with expected values for the equipment and outdoor conditions. If the readings suggest low charge, they may look for common signs such as oil residue near fittings, icing, or abnormal superheat/subcooling numbers. Many companies do a basic visual inspection during a tune-up; detailed leak detection (electronic detector, nitrogen pressure test, UV dye, soap-bubble testing on multiple joints) is often billed as a separate diagnostic because it takes longer. If refrigerant is low, the right fix is finding and repairing the leak rather than repeatedly adding refrigerant.

How long should an AC tune-up take, and what are red flags that it wasn’t done properly?

For a single system in average condition, a tune-up commonly takes about 45–90 minutes. Multi-system homes or very dirty units can take longer. Red flags: the technician never opens the panels, doesn’t take any electrical measurements, doesn’t check temperature split (supply vs. return), doesn’t look at the drain line, and doesn’t show you any readings or notes afterward. Another warning sign is “topping off refrigerant” without documenting pressures/temperatures or explaining why the charge is low. You should expect at least some measured results (amp draw, capacitor values, temperature readings, or similar) and a clear list of what was inspected and what needs follow-up.

Is a tune-up different for a heat pump system, or is it the same checklist?

A heat pump tune-up overlaps with an AC tune-up (coils, airflow, electrical checks, drain, thermostat, refrigerant readings), but there are extra items tied to heating mode. The technician should check the reversing valve operation, the defrost controls/sensors (for systems that use defrost), and confirm the outdoor fan and control board behave correctly in both modes. In many homes, they’ll also check auxiliary heat (electric heat strips or furnace backup), because a heat pump can appear “fine” in cooling yet struggle in heating if auxiliary heat isn’t staging correctly. If you rely on the heat pump year-round, it’s best that the visit includes testing both heating and cooling functions when outdoor conditions allow.