3 Places To Check For Blown AC Fuses

Your home's central air conditioning system needs electricity to run, but it also needs to protect itself from potential shorts and wiring faults. As a result, all modern air conditioning systems may have fuses or circuit breakers at numerous locations. These breakers can trip due to shorts, ground faults, and overloads, just like any other circuit breaker in your home. 

Of course, if a fuse or breaker trips, your air conditioner won't turn on. However, the symptoms of a blown fuse can be more varied than you might expect. Keep reading to learn about the three places you may need to check for a blown fuse in your AC system, along with some symptoms and possible causes for each one.

1. Disconnect Box

Your disconnect box should be close to your outdoor condenser unit. The typical disconnect box is a weather-sealed metal box with a door and some wires leading to the AC unit. If you aren't familiar with your home's disconnect box, it's good to locate it and determine how to open it. Knowing how to use your disconnect box will allow you to cut power to the AC if you need to perform future maintenance.

AC disconnect boxes come in two flavors: fused and unfused. If you see a simple switch in your box, you have an unfused variety and can move on to the next section. A fused box will contain either a circuit breaker or a fuse. Your condenser will stop running if this trips, although your indoor blower may still work. A tripped disconnect box fuse usually indicates a wiring problem at the outdoor unit.

2. Main Service Panel

Central air conditioning systems require their own 220/240V circuits, so you should have a labeled fuse or breaker in your main service panel for your AC system. This circuit may also include your air handler blower, although not all homes will have these two items on the same circuit. If you have an unfused disconnect box, any electrical issue with your AC system will trip this breaker.

Unfortunately, diagnosing a problem causing your main AC breaker to trip can be more challenging. You may have a wiring fault almost anywhere in the system, or the problem could be with the motor for your compressor, condenser fan, or air handler fan. You'll want a professional HVAC contractor to investigate the problem in most cases.

3. Control Board

Your AC system relies on low-voltage (24V) wiring for control signals and thermostat power. Most systems include a 24V fuse at the control board, which you can usually find near your air handler. Note that your furnace and AC may use the same control board. A fault in the low voltage wiring will pop this fuse but may not trip the main breaker.

Your control wiring runs to each thermostat and your condenser unit, so there are numerous locations for potential faults. Unless you can see damaged wiring, you'll usually want a professional to help you track down and repair the problem.

Reach out to an HVAC company for more information on air conditioning repairs.