TWO POLE CONTACTORS

  • Two pole contactors have two sets of contacts that switch.  This interrupts both sides of the incoming high voltage power to switch the unit off and on.
  • A two pole contactor can be used to replace a single pole contactor in most cases, it will simply break both sides of the incoming power.

ONE POLE CONTACTORS

  • One pole contactors (sometimes referred to as 1-1/2 pole) have one set of contacts that switch.  This interrupts only one side of the incoming high voltage power to switch the unit off and on.
  • The other side of the contactor is a jumper bar, or shunt, which allows power to flow through freely and does not provide any switching action.

TROUBLESHOOTING


DANGER-TROUBLESHOOTING SHOULD BE PERFORMED BY A TRAINED TECHNICIAN IN ACCORDANCE WITH ALL NATIONAL, STATE, AND LOCAL CODES AND LICENSING REQUIREMENTS.


Turn off all power to the unit before troubleshooting.


Often a contactor failure will be obvious.  If the points fail the contactor may be burnt or melted.


If the contactor appears to be physically intact, the 24 volt coil may have failed.  A volt-ohm meter can be used to perform a basic check.  First, verify that there are at least 24 volts present at the contactor coil.  If there is no 24 volt signal to the contactor, the problem is in the control circuit.  If 24 volts are measured at the contactor coil and it does not pull in, then the contactor is defective and should be replaced.  Also, if the contactor buzzes, hums, or chatters it should be replaced.


With the contactor pulled in, check for resistance from L1 to T1 and L2 to T2 with the ohm meter.  There should be zero or very little resistance across the contacts when they are pulled in.  If there is measureable resistance, replace the contactor.

ONE POLE CONTACTOR

TWO POLE CONTACTOR

CONTACTOR TROUBLESHOTING AND SELECTION


Be sure to turn off all power supplies to the unit before making repairs.


Servicing contactors presents a shock hazard.  Always double check  with a volt meter that all power is off before attempting any repairs.  Contactors should be serviced by a licensed professional in accordance with national, state, and local codes.


A contactor is a device that controls the flow of electricity to the compressor, fan motor, and other components of an air conditioner or heat pump.  The contactor is a magnetic switch that activates one or more poles to switch high voltage current from the incoming power supply to the load.  In most modern air conditioning applications the contactor is controlled by a 24 volt signal to the contactor coil from the thermostat.  All of the contactors we currently stock have 24 volt coils and will fail immediately if the wire connections are mixed up between the high voltage and low voltage terminals.


A contactor with enclosed contacts protects the contact points from the elements, dirt, and insects better than a contactor with open contacts.  Normally the cover over the contact points can be removed for inspection.


Contactors are rated by the amount of current flow (amps) they can safely handle.  A contactor can be replaced by one of a higher amp capacity for added durability, but never replace a contactor with one that has a lower amp rating.


Depend on Protactor® to keep your unit running strong.

REPLACEMENT CONTACTOR SELECTION
There are three criteria to consider when choosing a replacement contactor:

1. Verify that the existing contactor has a 24 volt coil and control circuit.

2. Is the existing contactor one pole or two pole?

3. Choose a contactor that has an amp rating equal to or greater than the existing part.