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What Are the Most Common Parts Needed for AC Replacement?

AC Technician | Anytime HVAC

What Your AC System Does

When you’re considering what parts you need for AC installation, it’s important to understand what you’re about to introduce into your home.

Your air conditioner is a closed system. It pumps refrigerant through pipes that run from your home’s indoor component to the outdoor AC unit. The system transforms the “state” of the refrigerant from a vapor into a liquid, and back again.

This transformation is the key to cooling.

Your air conditioning is based on the scientific principle of thermal equilibrium: in nature heat always flows from a hot object to a cold object. By transforming the refrigerant’s state – you’re making it either the hot object (to get rid of its heat) or the cold object (to absorb heat).

The Two Sides of Your AC System and its Parts

The air conditioning system has two halves:

1. The low-pressure half that includes the metering device and evaporator, which allow the liquid refrigerant to absorb your home’s heat.

2. The high-pressure half that includes the compressor and condenser, which allow the vaporized refrigerant to expel that heat outside.

Cold Liquid Absorbs Hot Air in the Evaporator

Inside your house, the refrigerant begins as a cold liquid that will absorb the warmth in your air. This happens inside the evaporator, a series of coiled copper pipes where the refrigerant is kept under very low pressure in order to quickly absorb heat.

Low pressure gives refrigerant an extremely low boiling point. It’s so low, that the cold refrigerant will boil into a vapor when the hotter room-temperature air touches it. Vaporizing allows the refrigerant to absorb your home’s heat, which it carries outside to the compressor.

Compression Raises Heat in the Vapor

The compressor is a pressure chamber that sucks in warmed, vaporized refrigerant from the low-pressure half of your AC system, and ejects it into the high-pressure half of your AC system. The reason for pressurizing the refrigerant vapor is to raise its temperature prior to entering the condenser.

Hot Vapor Gets Rid of Hot Air in the Condenser

Condensation is the transformation of a hot vapor into a cold liquid. The large fan in your outdoor AC unit blows cool air over the hot vapor in the condenser. Following the law of thermal equilibrium, all of the heat stored in the vapor flows into the cooler air, and the hot, vaporized refrigerant then transforms back into a cold, liquid refrigerant. This is why the outdoor AC fan wind always feels warm; the air has absorbed the heat that was once inside your home.

Cold Vapor is Depressurized to Absorb Heat Again

Under high pressure the now cool, liquid refrigerant flows back into your home and is depressurized by the metering device. This gives it the low pressure that will allow it to vaporize once again when it absorbs your home’s warm air.

Which of These Parts Fail the Most Often?

Thankfully, none of these parts are the most failure prone in your machine. This honor goes to contactor and start/run capacitor, which are two pieces of smaller electrical equipment that allow your machine to turn on and operate.

The fan motor (outside AC unit) or the blower motor (with the indoor evaporator) can also fail and need replacement.

Which is the Most Expensive to Repair?

Without question, the costliest part is the compressor, which is part motor and part vapor compressor. If, after 8 years the compressor fails, it may be time to think about buying an entirely new machine. If the compressor fails, it may jeopardize other parts of the system as debris from the motor and compressor sheathing infiltrate throughout.

For more information about what you can do to repair and maintain your AC, call Anytime for a free quote, routine help or emergency service 24/7.


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