I don't know that thinning it out will make it work with the different cartridges, that might not be the only problem. That said, to dilute it, you need to add a carrier oil.
An oil that is liquid at room temperature such as jojuba or avocado is probably your best bet.
edited to add: According to the ingredients list for Air Wick cartridges, they also contain ethanol, which might also dilute it and make it more watery as opposed to oily.