AC Troubleshooting Wizard - Burlington Heating And Cooling

AC Troubleshooting Wizard Burlington, ON

AC acting up? Walk through our step-by-step diagnosis guide before spending money on a service call.
Many common Burlington AC problems have simple fixes.

🩺 Step-by-Step

⏱️ 5 Minutes

🔒 Free

Before You Call Anyone — Check These First

A meaningful percentage of Burlington AC “emergency” calls turn out to be simple issues the homeowner could have addressed themselves. Running through this list before picking up the phone can save you the diagnostic fee and, in some cases, gets your AC running again in minutes.

1️⃣ Check the Thermostat

Is it set to COOL (not just FAN)? Is the set temperature actually lower than the current room temperature? Has someone accidentally switched it to HEAT? It sounds basic, but thermostat settings are the single most common source of “my AC doesn’t work” calls.

2️⃣ Check the Breaker Panel

AC systems use two circuits — one for the indoor air handler, one for the outdoor compressor. A tripped breaker on either circuit will stop the system. Reset any tripped breakers. If it trips again immediately, stop — that indicates an electrical issue needing a technician.

3️⃣ Check the Air Filter

A severely clogged filter restricts airflow so badly that the evaporator coil can freeze solid. A frozen coil produces zero cooling. Turn the system off (fan only for 2–3 hours to thaw), replace the filter, then restart. This fixes a surprising number of “AC not cooling” situations.

4️⃣ Check the Outdoor Unit

Is the outdoor condenser running? Can you see the fan spinning? Is it covered in debris — leaves, grass clippings, cottonwood fluff? A blocked condenser can’t reject heat. Turn the system off and gently clear any debris with a hose on low pressure.

5️⃣ Check the Condensate Drain

If you see water pooling near the indoor air handler or the system has a safety float switch, a blocked drain line can shut the system off. The drain line (usually a PVC pipe) can often be cleared by pouring diluted bleach or white vinegar into the drain pan access point.

6️⃣ Check the Disconnect Box

The outdoor unit has a disconnect box — usually a small metal box on the wall of your home near the condenser. If a previous owner pulled the disconnect for winter and forgot to replace it, the outdoor unit won’t run despite the thermostat calling for cooling.

Common Burlington AC Problems — Likely Causes

Symptom	Most Likely Cause(s)	Next Step
AC won’t turn on at all	Tripped breaker, thermostat issue, disconnect pulled	Check breaker/thermostat first
Runs but house not cooling	Low refrigerant, dirty coils, airflow restriction	Call technician
Warm air from vents	Thermostat set wrong, refrigerant issue, failed compressor	Check thermostat; call if correct
Ice on lines or unit	Low refrigerant or severely clogged filter	Turn off; check filter; call tech
Water dripping inside	Blocked condensate drain	Often DIY-fixable
Squealing or grinding noise	Failing fan or blower motor bearing	Turn off; call technician promptly
Clicking but won’t start	Failed capacitor or contactor	Call technician
Short-cycling (on/off fast)	Oversized unit, low refrigerant, thermostat issue	Call for diagnosis
Musty smell from vents	Mold in drain pan or ductwork	AC maintenance / duct cleaning

When to Call a Burlington HVAC Technician Immediately

Some AC problems require a certified HVAC technician — not because the homeowner isn’t capable, but because refrigerant handling, high-voltage electrical work, and certain mechanical repairs have legal and safety requirements in Ontario. Call Burlington Heating and Cooling directly in these situations:

🚨 Stop and Call Now

Breaker trips immediately after reset — indicates electrical fault, risk of fire or damage

Ice on refrigerant lines after filter has been replaced and system has thawed — refrigerant leak

Burning smell from any part of the system — shut off immediately at the breaker, call

Grinding, screeching, or banging — mechanical damage is worsening every minute it runs

Refrigerant handling of any kind — illegal without EPA/HRAI certification in Canada

System is 12+ years old and showing multiple symptoms — repair vs. replacement assessment needed

Frequently Asked Questions

My AC was working fine yesterday. Now it’s not. What happened?

Sudden failures often involve capacitors or contactors — components that can fail abruptly after years of gradual degradation. They’re among the more affordable repairs. It may also be a tripped breaker from an overnight voltage event. Start with the breaker check; if that doesn’t resolve it, a failed capacitor is the next most likely diagnosis and costs $175–$350 to repair.

How often should I change my AC filter in Burlington?

Every 1–3 months during the cooling season, depending on filter type and household conditions. Homes with pets, residents with allergies, or older ducted systems typically need monthly changes during summer. A 1-inch fiberglass filter needs monthly replacement; a thicker 4-inch media filter can last 3–6 months. Check monthly and change when you can’t see light through it.

Should I cover my outdoor AC unit in winter in Burlington?

No — at least not completely. Outdoor condensers are designed to withstand Canadian winters without covers. Fully covering them creates a warm, protected habitat for small animals that may chew wiring or build nests in the unit. You can place a piece of plywood on top (not sides) if you’re concerned about ice fall from a roof above, but leave the sides open for ventilation and critter deterrence. Remove any cover before starting the system in spring.

🚨 Emergency AC Repair

Burlington’s own HVAC team — available 24/7 for urgent cooling failures.