The answer to 'my condenser won't turn on' is that there are several common causes, including a tripped circuit breaker, a faulty contactor or capacitor, low refrigerant levels, or an issue with the thermostat or control board. The condenser is the outdoor unit of your HVAC system that houses the compressor and fan, and if it's not turning on, it can indicate a problem that requires troubleshooting.
If the condenser isn't running, first check the circuit breaker to make sure it hasn't tripped. Reset the breaker and see if that gets the condenser running again. If the breaker keeps tripping, there may be an electrical issue that needs to be addressed by a professional HVAC technician. You can also check the contactor, which is a relay that turns the condenser on and off - if the contactor is faulty, it may need to be replaced. Additionally, low refrigerant levels or a problem with the thermostat or control board could be preventing the condenser from turning on. These are more complex issues that are best handled by a licensed HVAC technician.