Depending on your type of heat pump / air conditioner, there are multiple ways to clean it.
Generally speaking, you must make sure the airways and filters are clear of any dirt or debris on a monthly basis, depending on how often you use your unit.
Every heat pump / air conditioner should have filters installed and these filters need to be washed to maintain optimum performance. Depending on the usage the recommended time frame between cleaning your filters will vary. If you use your unit daily, your filter should be cleaned at least once a month, and for those that use it less often, every three months should be sufficient. Please note that the cleaner the filter, the better the performance.