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Air Conditioner Sequence of Operation
Air Conditioner Sequence of Operation - When a technician is troubleshooting an air conditioner problem it is important that the technician understands the sequence of operation for that equipment. When there is a problem with the equipment, including air conditioners, the technician will know the problem if the equipment or air conditioner does not follow the sequence of operation. Sometimes it is that easy and other times it is not that easy when troubleshooting any type of HVAC equipment. However, it is important to understand the sequence of operation for an air conditioner so the technician can troubleshoot the air conditioner system.

Air Conditioner Sequence of Operation | HVAC Cooling

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Air Conditioner Sequence of Operation

Compared to other HVAC equipment an air conditioner sequence of operation is fairly simple. An air conditioner follows the following basic sequence of operation:

  1. The thermostat, set to cooling mode, calls for cooling. The switch inside the thermostat closes. This energizes the “Y” and the “G” circuit in the thermostat or the compressor contactor and the fan circuit.
  2. The compressor contactor closes and the condenser fan motor and the compressor turns on. This happens simultaneously as the compressor contactor controls both the compressor and the condenser fan motor. This is important because if the compressor contactor pulls in or engages and the fan doesn’t start but the compressor does then the technician knows there is a problem with the condenser fan motor and vice versa. If neither starts but the contactor is pulled in then the technician knows there is either a problem with the contactor passing voltage across the contacts or a power problem. If the contactor does not pull-in then the tech knows there is a control problem.

    Condenser - Air Conditioner - Heat Pump Fan Motor

    Condenser Fan Motor

  3. At the same time the compressor contactor is doing its job the blower fan relay closes (from the “G” contact in the thermostat) and energizes the blower fan. While the compressor gets the refrigerant moving through the refrigeration system the fan begins moving air through the duct system and across the evaporator coil.
  4. When the thermostat satisfies the “Y” and the “G” contacts in the thermostat open de-energizing the compressor contactor and the fan relay. The compressor and condenser fan motor de-energize and stop operation. The fan, in heating and cooling mode (no matter what type of heat you have) will remain on because of a time delay in the air handler.This is to dissipate any cool or hot air left in the duct system. It adds efficiency to the system and makes use of any residual energy left in the system. In heating mode it also allows for a cooling down of the heat left in the system.

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Air Conditioner Sequence of Operation | The Basics

Adding some basics to the air conditioner sequence of operation along with some field experience one can become competent in air conditioner troubleshooting. Some basics for becoming a good air conditioner technician include both practical and theory skills and knowledge:

Finally, in conclusion that is the basic air conditioner sequence of operation used in millions of air conditioners all over the world. Essentially, air conditioner sequence of operation is how an air conditioner works. Even if you know the sequence of operation for an air conditioner there are many other problems that can occur with an air conditioner that cannot be solved with this knowledge alone. Some things take education and experience to figure out. For an HVAC technician this is a basic and helps in solving air conditioner problems.

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Air Conditioner Sequence of Operation

 

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