🔥 The Ultimate HVAC Emergency Checklist: 80+ Critical Issues That Demand a Hotline Call

When your heating or cooling fails, the problem can range from a minor inconvenience to a serious safety hazard. For homeowners and businesses in Toronto, knowing exactly when to call for 24/7 emergency HVAC repair is essential. This exhaustive list details over 80 critical and urgent failures that require immediate professional attention from a TSSA-licensed technician. Don’t wait, if your issue is on this list, contact the hotline immediately for dispatch!

Category 1: Life Safety & Fire Risk (Issues 1-10)

These issues require you to shut down the unit (if safe) and call for emergency dispatch immediately.

#	Emergency Issue	Risk Assessment
1.	Carbon Monoxide (CO) Alarm Activation	EXTREME: Health/Life Threat
2.	Strong Gas/Sulphur Smell Near Unit	EXTREME: Explosion/Fire Risk
3.	Visible Flames, Sparks, or Smoke from Unit/Panel	EXTREME: Fire Hazard
4.	Total Furnace/Boiler Failure in Sub-Zero Temperatures	HIGH: Frozen/Burst Pipe Risk
5.	AC Condensate Line Backup Causing Ceiling/Wall Flood	HIGH: Water Damage & Mold Risk
6.	Leaking Boiler or Hot Water Heater Causing Active Flooding	HIGH: Water Damage & System Failure
7.	Loud Explosion or Metallic Banging from Inside the Unit	HIGH: System Catastrophe/Safety Risk
8.	System Failure affecting vulnerable persons (elderly/infants)	HIGH: Health Risk
9.	Visible Burnt Wiring Smell from the Furnace or Air Handler	HIGH: Electrical Fire Risk
10.	Emergency Electrical Disconnect Switch is Faulty or Hot	HIGH: Electrical Hazard

Category 2: Urgent Heating System Failures (Issues 11-40)

These issues compromise efficiency, comfort, and safety, demanding immediate service.

#	Component	Urgent Failure Description
11.	Ignition	Pilot light goes out repeatedly or igniter fails.
12.	Combustion	Yellow or orange pilot light flame (potential CO risk).
13.	System	Furnace refuses to turn on at all.
14.	System	Furnace short-cycles (turns on and off rapidly).
15.	Airflow	Vents blowing cold air when heat is demanded.
16.	Blower	Blower motor runs constantly (won’t shut off).
17.	Blower	Strange grinding or screeching noises from the blower.
18.	Thermostat	Thermostat is blank or fails to command the system.
19.	Electrical	Fuse or breaker constantly trips when heat starts.
20.	Boiler	Boiler pressure drops rapidly or is dangerously high.
21.	Boiler	Radiators are completely cold despite boiler running.
22.	Ventilation	Condensate drain line is frozen or blocked (causing system shutdown).
23.	Ductwork	Loud whistling or rattling sounds in ducts.
24.	System	Soot build-up visible around the furnace or flue.
25.	Blower	Blower motor cycles on and off too frequently.
26.	Electrical	Capacitor failure (motor hums but won’t start).
27.	Ventilation	Flue pipe or exhaust pipe blockage.
28.	Boiler	Circulator pump failure (no heat distributed).
29.	System	System vibrating excessively upon start-up.
30.	Ductwork	Supply vents restricted due to obvious duct collapse.
31.	Boiler	Expansion tank is leaking or waterlogged.
32.	Thermostat	Thermostat setting does not match indoor temperature (major variance).
33.	Ignition	Intermittent burner firing (short periods of heat).
34.	Airflow	Weak airflow due to heavily clogged coil (for heat pumps).
35.	System	Sudden and unexplained spike in gas consumption.
36.	System	Error codes constantly flashing on the display panel.
37.	Boiler	Pressure relief valve is constantly dripping/releasing water.
38.	Ductwork	Excessive noise/vibration from the duct fan motor.
39.	Blower	Blower motor fails to start during a call for heat.
40.	Ventilation	Poor furnace efficiency due to cracked heat exchanger.

Category 3: Urgent Cooling System Failures (Issues 41-70)

These issues impact comfort and efficiency, especially during high heat warnings.

#	Component	Urgent Failure Description
41.	Cooling	AC unit blows only warm or room-temperature air.
42.	Cooling	AC unit is completely freezing up (ice on line/coil).
43.	Compressor	Compressor cycles on and off quickly (short cycling).
44.	Compressor	Compressor hums loudly but fails to start.
45.	Refrigerant	Hissing noise (potential active refrigerant leak).
46.	Drainage	Drain pan is overflowing and risking water damage.
47.	Drainage	Condensate pump failure or blockage.
48.	Outdoor	Condenser fan is not spinning when the unit is running.
49.	Outdoor	Unit is vibrating heavily and making loud metallic noises.
50.	Indoor Unit	Air handler is making loud knocking or thumping sounds.
51.	Indoor Unit	Water pooling around the indoor air handler unit.
52.	Controls	AC contactor is burned out or stuck in the ‘on’ position.
53.	Controls	Fuse is blown in the outdoor disconnect box.
54.	Refrigerant	Visible oily residue near the refrigerant line connections.
55.	Heat Pump	Defrost cycle runs too frequently or constantly.
56.	Heat Pump	Auxiliary/emergency heat constantly engages during mild weather.
57.	Sensors	High-pressure limit switch tripping repeatedly.
58.	Sensors	Low-pressure switch tripping repeatedly.
59.	Ductless	Mini-split unit displays a flashing light or error code.
60.	Ductless	Ductless head unit is actively dripping water indoors.
61.	Cooling	Unit runs constantly but never reaches set temperature.
62.	Cooling	Significant drop in cooling capacity during peak heat.
63.	Cooling	Loud, persistent rattling or squealing from the outdoor unit.
64.	Outdoor	Condenser unit is excessively dirty and overheating.
65.	Cooling	Heat pump is stuck in one mode (cooling or heating).
66.	Compressor	Compressor runs, but the unit is not cooling.
67.	Refrigerant	Bubbling or gurgling sounds from the refrigerant lines.
68.	Indoor Unit	Frozen filter or coil due to extreme dirt blockage.
69.	Controls	Transformer burnout (total unit electrical failure).
70.	Indoor Unit	Excessive mold or mildew visible on coils or in air handler.

Category 4: General & Air Quality System Failures (Issues 71-80)

These issues affect the overall system health, efficiency, and indoor air quality.

#	Component	Urgent Failure Description
71.	Zoning	Zoning damper motor failure (cannot switch zones).
72.	Zoning	Certain zones are receiving no heat or no cool air.
73.	Air Quality	Ventilation system (HRV/ERV) is completely non-functional.
74.	Air Quality	Humidifier fails to provide moisture during dry winter months.
75.	Air Quality	Air purifier/UV light component fails to turn on.
76.	Whole House	Sudden, significant temperature difference between floors.
77.	Whole House	Unexplained, persistent high carbon dioxide (CO2) levels indoors.
78.	Ductwork	Main duct trunk line is visibly disconnected.
79.	Controls	System won’t respond to any manual controls at the unit.
80.	System	Total electrical failure after severe storm/lightning strike.

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