Process

• One hose of the cleaner attaches to a suction port a pool uses to draw water into its filtration system. The cleaner uses this vacuum to create suction. This suction moves the cleaner across a pool as it cleans. While some cleaners move randomly, others are designed to move in set patterns that are controlled by turning the suction on and off through an intermittent valve.
  
  

Suction

• The most common problem with pool cleaners is suction. Sometimes, a cleaner has too little suction and refuses to move. This is caused by a blockage or a kink in the hose that interferes with the vacuum. There are instances, too, when there's simply too much suction. In these cases, the cleaner sucks in air from above the water's surface, which can be hazardous to the system.
  
  

Filters

• Some cleaners have separate filters, while others simply pass water into the pool's natural filtration system. Either way, these filters need to be cleaned. If dirt builds up on a filter, it can block the suction of the water, leaving the cleaner unable to effectively pick up any other particles.
  
  

Gearbox

• Pool cleaners that move in set patterns use a gearbox to direct these movements, telling the valves when to switch on and off. This gearbox can malfunction and cause the cleaner to stop moving or make it move erratically. When this happens, the cleaner often needs to be replaced.
  
  

Hoses

• The hose that the cleaner uses to direct water into the pool pump can sometimes become tangled. This impedes the cleaner's movement and compresses the hose, cutting off suction. These hoses can also be tripped over and accidentally damaged.