# AC running but blowing warm air

> Scope: CA (Canada) · Language: en-CA · Version: 1
> Prepared for Canada using the Canadian Electrical Code and provincial rules. Not intended for use outside Canada.

The most common cause is a failed run capacitor — a $10–45 part that fails far more often than any other AC component. Check it first: shut off power at the breaker and look for a bulged or leaking top. Other likely causes, in order: dirty condenser coils and a clogged air filter causing a frozen evaporator coil.

## Likely causes, in the order to check them

1. **Failed run capacitor** (A worn-out capacitor) — share ~28%, DIY possible, safety-critical step — read the gate (hvac)
2. **Dirty condenser coils** (The outdoor unit can't shed its heat) — share ~23%, beginner-friendly
3. **Clogged filter / frozen evaporator** (A clogged filter froze the system) — share ~20%, beginner-friendly
4. **Low refrigerant (a leak)** (The system is low on refrigerant) — share ~12%, call a licensed pro (hvac)
5. **Failed condenser fan motor** (The outdoor fan has quit) — share ~9%, call a licensed pro (hvac)
6. **Thermostat set wrong or unpowered** (A thermostat issue) — share ~8%, beginner-friendly

## Observable conditions that re-rank this list

- The outdoor fan isn't spinning
- The outdoor unit is humming
- There's ice on the copper pipes
- Something smells hot or burnt at the unit ⚠️ (escalation — stop and get help)

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Full interactive page: https://check.robc.onl/symptoms/runs-blows-warm
JSON twin: https://check.robc.onl/symptoms/runs-blows-warm.json