hi, the wife has a farm that needs needs to be temperature controlled, so we use an evap system, (ie when the  temp gets to X  the water pump  starts to push water through pad (paper) at front end of farm - then drawn through the farm by fans the back... when temp is at the right level it shuts down) this is where the double/treble click takes place from the megnetic contactor at the bottom end which is the water pump "in". the megnectic contactor is s-n series mitsubisih (running same system for 7 plus years) i thought maybe the m/c was on its  way out so replaced unit, but still getting said problem. 

m/c is wired up electric in at top end/ thermostat top end/ pump in at the bottom. change the m/c every couple of years... usually. any ideas why this happens?

Have you replaced the thermostat?

 

They are supposed to "snap" over when at temperature but may not as they age.

 

 the thermostat is an import from the usa, will have to make enquries..... makes sense since this controlls the on off, thanks