SINGLE AND DOUBLE POLE CONTACTORS

[nadercorner]

What is the difference between Single Pole and Double Pole Contactors and on what basis we choose this or that and what is the wiring diagram for both with the crank case heater??

[rmuntz]

http://www.youtube.com/watch?v=au_vyaA1zsU&feature=related

[Rustymike]

the primary purpose of most manufacturers using a single pole contactor all relates to cost.
I have found when having to replace a single pole contactor that using a larger amp rated contactor will last longer that the mostly marginally sized one that was factory installed.
There have been times when I've used a 2 pole contactor instead, and just had to relocate the CC heater wires to the line side on L1 so the compressor was kept warm.
If you find the contactor points had been flash welded, badly pitted or arc burned, double check the compressor voltage, start up and running amp draws and also check out the run cap to see if it's starting to fail, after you replace the contactor.
Never assume that just by replacing the 1 failed part, the contactor, has solved your no cooling problem!