Most alarms are about the seal. A common mechanical problem is ineffective therapy delivery due to loss of suction, most often caused by an inadequate seal around the dressing.
There are other causes too: improper suction tube placement, tube blockage, loss of battery power, or a full canister. Which of those you are expected to check yourself depends on the device you were given, and the instructions that came with it are the authority on that — not a general page.
An alarm is not something to leave until morning. Loss of suction should be remedied as soon as it is detected to avoid any disruption in negative pressure therapy. Here’s what can follow if it is left: loss of negative pressure in heavily draining wounds can result in uncontrolled drainage that saturates the wound, dressing, and surrounding skin. Prompt cleansing is then necessary to prevent skin breakdown and support ongoing healing.
The fixes themselves belong to whoever manages your dressing. If the device alarms, the dressing seal may need reinforcement with additional adhesive, or the dressing may need to be replaced. Both of those are clinical steps. This page will not teach you to re-tape your own seal, and nothing here should be read as permission to open the dressing.
So the practical answer is a phone number. Every system has its own manufacturer’s instructions and alarm codes, and the team who set yours up is the authority for your machine. If you have not been given a number to call after hours, ask for one before you need it — that is a better question to ask in daylight than at two in the morning with a machine beeping.