Why won't my AC turn on?

Q: How much does it cost to fix ac won't turn on at all?

$100–$600. Often just a diagnostic fee if it's a reset. Capacitor or contactor replacement is modest. Control board replacement is the upper end.

Q: Can I fix ac won't turn on at all myself?

There are some safe steps to try first. Call if the breaker trips again immediately, if you smell burning, or if power and thermostat both check out and it still won't start. A breaker that trips repeatedly is a warning, not a nuisance.

Short answer

Start with power and settings before assuming the worst. A tripped breaker, a thermostat with dead batteries or set to the wrong mode, a blown fuse, or a safety switch that's done its job all stop the system entirely — and several of those you can check yourself in a few minutes.

Urgency: Address soon
DIY: Some steps you can try
Typical cost: $100–$600
Time: 1–2 hours

Address soon

Treat as urgent in extreme heat or if anyone in the home is medically vulnerable to high temperatures.

What's happening

Nothing is running: no blower indoors, no fan outdoors. That usually points to power delivery or a control signal rather than the cooling components themselves.

Most likely causes

01
Tripped breaker
Both the indoor air handler and outdoor unit usually have their own breakers. Either one can stop the system.
02
Thermostat problem
Dead batteries, wrong mode, or a schedule holding a setting can all look like a broken air conditioner.
03
Condensate float switch tripped
A safety device deliberately shuts the system down when the drain pan fills, to prevent water damage.
04
Blown fuse on the control board
A small low-voltage fuse protects the control circuit and can fail after a surge.
05
Failed capacitor or contactor
The unit may hum without starting, or do nothing at all.
06
Disconnect switch off
There's usually a pull-out disconnect near the outdoor unit that may have been left off after service.

What you can try yourself

1Replace the thermostat batteries and confirm it's set to COOL with a target well below room temperature
2Check the breaker panel — reset any tripped breaker once, firmly to OFF then ON
3Check the disconnect switch near the outdoor unit is engaged
4Look at the drain pan; if it's full, the float switch has likely cut power on purpose
5Make sure the indoor unit's service door is fully closed, as many have a safety interlock

When to call someone

Call if the breaker trips again immediately, if you smell burning, or if power and thermostat both check out and it still won't start. A breaker that trips repeatedly is a warning, not a nuisance.

Who to call

HVAC technician

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What it should cost

$100–$600

Often just a diagnostic fee if it's a reset. Capacitor or contactor replacement is modest. Control board replacement is the upper end.

Estimates are typical US ranges for orientation. Actual pricing varies by region, home and contractor — always get a written quote.

What happens if you wait

A breaker that trips repeatedly can indicate a short or a motor drawing too much current — a genuine fire risk. Don't keep resetting it.

Questions to ask the contractor

What caused it to stop?
If a breaker tripped, what was drawing too much current?
Is anything here a safety concern?
What can I check myself before calling next time?

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