Recently, there has been much discussion about running a central air conditioner during rain. This has been standard advice for many years in window and split air conditioners, as they are likely to draw moisture into the pipes, and eventually into the machine. However, this is not true for a central air conditioner, which runs internally.
Running a Central Air Conditioner during Rain
The air con unit installed in many homes does not bring in air from outside, instead it cools the air surrounding the conditioner with Freon. There is no reason why the air conditioner cannot be used, unless there is a thunder storm, in which case it is best to turn off electrical appliances. Central air conditioners are fully protected against rain and snow, so the effects of running a central air conditioner during rain should be—none. If there are effects, this is a sign that the air con was badly installed in the first place.
There has been advice given recently by people while installing the central air conditioner. This is either an urban legend which has become a popular myth, or it is due to poor work by the engineer, which they are attempting to hide by warning against the effects of running the AC unit in rain.