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🍁 Conçu pour les foyers canadiens — rédigé selon les codes canadiens et les règles provinciales. N’est pas destiné à un usage hors du Canada.

AC running but blowing warm air

Annoying — but usually not a disaster. Most of the time this is a $20 part or a free fix.

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Check the run capacitor first. It's the single most common reason a running AC blows warm air — and checking is free. Turn off power at the breaker, open the small side panel, and look at the round canister: a healthy one has a flat top.

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Causes probables, dans l’ordre à vérifier

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Pour débutant Faisable, avec soin Sécurité critique Appelez un pro

visibilityHow to check

  1. Turn the AC off at the breaker panel AND pull the gray disconnect near the outdoor unit.
  2. Unscrew the small side access panel on the outdoor unit.
  3. Look at the round canister's top. Flat is fine. Puffed up or leaking means it's failed.
buildscrewdriver schedule15 min

handymanHow to fix it

report One rule before you touch itCapacitors hold a strong electric charge even after the power is off — and a dual run capacitor holds it on more than one pair of terminals. Short across each pair (Common-to-HERM, then Common-to-FAN) with an insulated discharge tool before touching any terminal. If that step doesn't sit right with you, stop: for a pro this is a quick, inexpensive visit.

Photograph the wiring, discharge the old capacitor, swap in a replacement with the same µF and voltage rating, reconnect wire-for-wire.

schedule30 min savings$14–28
Dual run capacitorMatch the µF and voltage printed on your old canister $14–28 open_in_new Insulated capacitor discharge tool
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gavel Vérifiez d’abord votre province AB: permis au propriétaire · BC: permis au propriétaire · ON: permis au propriétaire · PE: permis au propriétaire · QC: permis au propriétaire
Component replacement on the line-voltage side of owner-occupied equipment; no refrigerant handling involved.

visibilityHow to check

  1. Walk out to the outdoor unit and look at the metal fins around its sides.
  2. A gray blanket of dust, grass clippings, or cottonwood fluff on the fins means the unit can't shed heat — that's the whole diagnosis.
  3. While you're there, clear anything crowding the unit: it wants about 60 cm of open air on all sides.
buildAucun outil schedule2 min

handymanHow to fix it

warning Power off before waterKill the power at the disconnect or breaker before rinsing. Water and a running condenser don't mix, and the fan can start on its own when the thermostat calls.

Turn off power at the outdoor disconnect, then rinse the fins gently with a garden hose from the inside out if you can, or top-down from outside. No pressure washer — it folds the fins flat. Let it dry, restore power.

  1. Turn the AC off at the thermostat, then pull the gray disconnect near the outdoor unit (or flip its breaker).
  2. Rinse the fins with a garden hose at normal pressure, working top to bottom. Never use a pressure washer — it flattens the fins and makes things worse.
  3. If the mat of debris is thick, a soft brush stroke in the direction of the fins (never across) loosens it first.
  4. Let the unit dry for a half hour, restore power, and give it 15 minutes of runtime before judging the result.
schedule20 min savingssouvent gratuit

visibilityHow to check

  1. Pull the air filter and hold it up to a light. If you can't see light through it, it's choking the system.
  2. Check the copper lines at the indoor unit and outdoor unit for frost or ice. Ice plus weak airflow is the classic frozen-coil pattern.
  3. Weak, cool-ish air from the vents (not warm, not cold) is the other tell — the coil is iced over and air can't pass through it.
buildAucun outil schedule5 min

handymanHow to fix it

Switch the system to FAN ONLY (cooling off) and let the ice melt fully — typically 2 to 4 hours. Fit a fresh filter, then run cooling again. If it re-freezes with a clean filter and open vents, stop there: persistent freezing points to refrigerant or airflow issues a technician should chase.

  1. At the thermostat, turn cooling OFF and the fan to ON. The moving air thaws the coil from the inside; expect 2–4 hours.
  2. While it thaws, fit a new filter — match the size printed on the old one's frame. Note the airflow arrow on the frame; it points toward the furnace/air handler.
  3. Open any closed supply vents; a starved system freezes again even with a clean filter.
  4. Run cooling and check the lines an hour later. Re-freezing with a clean filter and open vents means it's time for a technician.
schedule15 min savings$8–15
Furnace/air-handler filterMatch the size printed on your old filter's frame (e.g. 16×25×1)

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Finding a leak, repairing it, and recharging the system means opening the sealed refrigerant circuit. In Canada that work is restricted to certified technicians under federal halocarbon rules — it isn't a homeowner task in any province, and venting refrigerant is an offence. The good news: your observation ("ice on the lines, weak cooling for weeks") is exactly the head start a tech wants.

report Sealed-system work is licensed-onlyThe reversing valve and refrigerant charge are part of the sealed system. In Canada, working with refrigerant requires certification, and valve replacement means brazing on pressurized lines. This is a licensed HVAC repair — a technician can confirm it quickly.
gavel Vérifiez d’abord votre province AB: réservé aux licenciés · BC: réservé aux licenciés · ON: réservé aux licenciés · PE: réservé aux licenciés · QC: réservé aux licenciés
Refrigerant handling requires certification across Canada under the federal Ozone-depleting Substances and Halocarbon Alternatives Regulations; provinces layer their own trade licensing on top.

Vos notes accompagnent la demande — ce que vous avez vu, ce que vous avez éliminé, quand ça a commencé — pour que le pro arrive avec une longueur d’avance.

verifiedPourquoi confier ceci à un pro

Swapping the motor means working inside the unit at the capacitor and line-voltage wiring, and matching the motor's specs exactly. Meanwhile, running the system with a dead fan can overheat the compressor — the most expensive part in the machine. Keep the system off until it's fixed.

Vos notes accompagnent la demande — ce que vous avez vu, ce que vous avez éliminé, quand ça a commencé — pour que le pro arrive avec une longueur d’avance.

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Pourquoi la liste est dans cet ordre

Nous ne classons pas seulement selon la probabilité. Nous classons comme le ferait un bon artisan honnête : éliminer d’abord les causes gratuites, sûres et courantes. C’est pourquoi les vérifications peu coûteuses passent avant les réparations chères — et pourquoi tout ce qui est dangereux reçoit un arrêt net plutôt qu’un encouragement. Cet ordre existe pour vous faire économiser, pas pour vous vendre quelque chose.