They don’t recommend the use of any air freshener or oils in conjunction with the stick/full size vacs. Any negative impact caused, isn’t covered under their warranty. If deciding to use it, I am not really sure where it would go. If it smells bad, you might be better off washing or replacing the filter. Give Cordless vacuum smells like a wet dog - Help | Dyson Community a read. 

When it comes to using air fresheners with a cordless vacuum cleaner, it is generally not recommended to use them directly inside the vacuum or combine them in any way. Cordless vacuum cleaners typically have a specific purpose of cleaning dirt, dust, and debris from surfaces, while air fresheners serve to improve the scent and freshness of an environment. Mixing the two can lead to unintended consequences and potentially damage the vacuum cleaner or compromise its performance.

Air fresheners usually come in various forms, such as sprays, plug-ins, or scented discs. It's important to follow the manufacturer's instructions and use them as intended in separate areas or away from the vacuum cleaner. For instance, you can freshen the room after vacuuming or place air fresheners strategically in different parts of your living space.

If you're concerned about odors while using a dyson cordless vacuum cleaner, it's worth noting that many modern vacuum models come equipped with built-in filtration systems that effectively capture and contain particles, reducing unpleasant smells. Additionally, regularly emptying and cleaning the vacuum's dustbin or filter can help maintain a fresh environment during and after cleaning sessions.

Remember, it's always a good idea to consult the specific user manual and guidelines provided by the manufacturer of both your cordless vacuum cleaner and air freshener products to ensure proper usage and avoid any potential issues.