Electrical Contactors For Heat Pumps & Air Conditioners
Most heat pumps and central air conditioning systems have a high-voltage switching device in the condensing (outdoor) unit called a contactor. Most contactors are controlled by a low-voltage electrical circuit which magnetically energizes a coil causing its metal contacts to engage (close). This supplies high voltage to the compressor, fan motor and any other high-voltage components.
Standard contactors have one, two or three sets of contacts (poles) depending on the system's electrical requirements. A double pole contactor has two sets of contacts and both need to be engaged (closed) for the unit to work properly. A single pole contactor allows one leg of the high-voltage circuit to constantly supply power to a component. You will find these mostly in heat pumps. The heat pump's compressor has a heater that warms its oil in cold conditions.
If you find that an outdoor condensing unit is not running and the poles are open, do not assume it's a defective contactor. TECH NOTE: Remember, just because the contacts show open, there is still high voltage supplying the contactor! Turn the power off to the condensing (outdoor) unit before handling a contactor.
There are so many reasons why a contactor would show open. Check for low voltage current supplying the magnetic coil. If you are getting proper low voltage readings, check the contactor for defects like burnt or pitted metal contacts. Make sure there is nothing from causing the contacts not to close like insects, spider nests or dirt. If the high-voltage electrical connections on the contactor shows burnt wires or even melting, there is a high voltage problem in a component causing this.
Do not replace a contactor assuming this will remedy the problem. The component or reason this occurred (burnt wires or melting) needs to be repaired. If you are not getting a low voltage current to the contactor's magnetic coil and the metal contacts look clean, there is a problem with the system's low-voltage circuit wiring or a low-voltage sensor or device (ie. thermostat, temperature sensors, limits, circuit board, transformer, etc.) that is causing the problem. TECH NOTE: If you find that the contacts are closed and you are getting the proper voltage coming to and from the electrical connections on both sides of a contactor, you have a defective high voltage component.
If you find that the contactor is defective, replace it with the same type (poles), voltage and ampere (amp) rating. The easiest way to replace a contactor is wire-to-wire from old to new. TECH NOTE: When removing a contactor or contactor's wires, turn off power to BOTH outdoor and indoor units. (ie. condenser and air-handler / condenser and furnace).
The vendors' websites, listed below, contains online information on electrical capacitors for HVAC systems.
HVAC Contactors and Control Relays Online
|Parts-HVAC:Contactors and Relays for HVAC are available at Wholesale and Quantity Pricing. Shop our Parts HVAC Online Store for Transformers, Contactors, and Relays HVAC Supplies and Accessories. Also find hard to find Transformers, Contactors, and Relay replacement parts.|
|Eaton:Eaton offers the most complete line of definite purpose contactors and motor starters in the industry.|
|Grainger:Motor Contactors & Electrical Contactors - Motor Controls - Grainger Industrial Supply|
|AC Pro:HVAC Contactors - AC Contactors - Air Conditioner Contactor - ACPro.com|
|HVAC Parts Outlet:We have the contactor for your HVAC unit! Contact us if you require assistance.|
|Carrier Enterprise:Shop for HVAC contactors & other HVAC electrical accessories here. Carrier Enterprise is your one stop shop for HVAC parts and supplies!|
|HVAC Parts Online:Here you will find our selection of top quality contactors and relays for the HVAC industry. Heating and cooling equipment required high voltage controls that can endure thousands of cycles under extreme conditions. We offer only heating and cooling contactors and relays that can live up to those standards.|
|Arnold's Service Co.:Let us help you repair your air conditioner or heat pump! We sell many different brand new OEM heat pump and AC contactors.|
|Presto:Contactors - HVAC | Presto Maintenance Supply|
|Shorty's HVAC Supplies:Contactor, Relay | ShortysHVAC.com|
|Emerson:Emerson contractor products include SureSwitch, a universal electronic upgrade for mechanical compressors, and 94 and 90-series, 1.5 and 2-pole mechanical contactors.|
|My HVAC Parts:Contactors for Air Conditioners and Heat Pumps | MyHVACParts.com|
|HVAC Parts Shop:We Have Thousands Of Genuine Lennox HVAC Repair Parts, Filters and Accessories In Stock & Ready To Ship Right To Your Home. Order From HVACPartsShop Today!|
|Lennox Pros:You can never have enough contactors. Shop Lennox's contactors and electrical components at LennoxPros.com.|
|Menards:Eaton 30-Amp 2-Pole 24V Definite Purpose Contactor | Menards.com|
|NECC:In stock for immediate shipment Honeywell 30-75Amp contactors. 2 pole, 3 pole. Same day shipment from stock, Authorized Factory Distributor-NECC|
Direct from the Tech...
If an HVAC Contactor Could Talk
|This article explains that by looking at the electrical contactor on a heat pump or air conditioning system could help locate the problem.|
HVAC Replacement Parts
|Capacitors: HVAC Systems|
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