A method and apparatus are disclosed for applying negative pressure to a wound site. The apparatus comprises a source of negative pressure a processing element and a memory comprising instructions configured to when executed on the processor cause the apparatus to perform the steps of via the source of negative pressure attempting to generate a desired negative pressure at the wound site if the desired negative pressure has not been generated after a first predetermined period of time deactivating the source of negative pressure for a second predetermined period of time and subsequently attempting to generate the desired negative pressure at the wound site.
