That acrid, burnt smell emanating from your outdoor AC unit is never a good sign. It indicates something is amiss and needs attention. Ignoring it could lead to more significant problems and expensive repairs. This post will explore the common causes of a burnt smell from your outdoor AC unit and guide you on what to do.
Identifying the Source of the Smell
The first step is to pinpoint the source. Is the smell consistently present, or only when the unit first turns on? Is it a sharp, electrical smell, or more of a burning plastic or rubber odor? Knowing this helps narrow down the potential issues. 
Overheating Compressor
One of the most common causes is an overheating compressor. The compressor is the heart of your AC system, and if it’s overworked or restricted (due to dirty coils, for example), it can overheat and produce a burning smell. Regular maintenance, such as cleaning the coils as described later, can help prevent this.
Electrical Issues
A burning smell could also indicate an electrical problem. This could range from minor issues like loose wiring to more serious problems such as a failing capacitor or motor. Never attempt to diagnose or repair electrical components yourself; always call a qualified HVAC technician. 
Dirty or Restricted Airflow
Restricted airflow is a significant contributor to overheating and burnt smells. Leaves, debris, and overgrown vegetation can block airflow to the condenser coils. Regular cleaning of these coils is crucial for optimal performance and to avoid a burnt smell. Learn more about cleaning your AC unit.
Low Refrigerant Levels
Low refrigerant levels can cause the compressor to work harder than necessary, leading to overheating and a burnt smell. Refrigerant leaks require professional attention. You should contact an HVAC professional for proper diagnosis and repair. 
Failing Blower Motor
The blower motor is responsible for circulating air through the system. If it fails or is malfunctioning, it can overheat and cause a burning smell. A failing blower motor will often also be accompanied by unusual noises. Consider replacing the motor if the issue persists. You can check our guide on common AC problems and solutions.
Overloaded Circuit Breaker
Sometimes, the problem isn’t with the AC unit itself but with the electrical supply. An overloaded circuit breaker can cause the unit to malfunction and produce a burning smell. Check your breaker box to see if the breaker is tripped. If so, reset it, but if it trips again immediately, call an electrician.
Belt Problems (for units with belts)
Older AC units may use belts to power the blower. A worn, loose, or broken belt can cause the motor to overheat and emit a burning smell. Regular inspection and replacement of belts are necessary to avoid this. [IMAGE_4_HERE]
Conclusion
A burnt smell from your outdoor AC unit is a serious issue that shouldn’t be ignored. By understanding the common causes and taking appropriate action, you can prevent more significant damage and ensure your AC unit continues to operate efficiently. Remember to always prioritize safety and call a qualified professional for electrical issues or refrigerant leaks. Find a local HVAC technician here.
Frequently Asked Questions
What should I do if I smell burning? Turn off your AC unit immediately to prevent further damage.
How often should I clean my AC unit? Cleaning your AC unit’s coils at least once a year is recommended, ideally before the summer season begins.
Can I fix a burning smell myself? For electrical or refrigerant issues, it’s best to call a professional. Minor issues like cleaning coils can often be handled yourself.
How much does an AC repair typically cost? The cost varies greatly depending on the issue and the location. It’s best to get a quote from a local HVAC repair service.
What are the signs of a failing compressor? Besides a burning smell, other signs include unusual noises, poor cooling performance, and frequent cycling on and off.
