What is the A/C Suction Line?
On your exterior condensing unit, or what you might refer to as the outside air conditioning unit, there are two lines connecting the exterior unit to the house. Those lines are called the A/C suction line and the A/C liquid line. These lines have opposite functions. The liquid line is responsible for transferring the liquid form of the coolant, or refrigerant, from the exterior system to the interior system. While the suction line is responsible for pulling the gas vapor refrigerant back to the exterior unit for the recycling process which occurs within the compressor. This “refrigerant loop” occurs continuously when your A/C unit is turned on.
The A/C Suction Line and Refrigerant
The refrigerant runs in a continuous loop between the interior and exterior system and is responsible for starting and continuing the cooling process. The refrigerant shifts between being a liquid or a gas depending on where it is in the loop. Without refrigerant, air temperatures cannot be controlled and the desired cooling temperature cannot be achieved using the interior control systems.
The A/C Suction Line and the Compressor
Inspector Lance | Author
The outdoor unit houses a compressor, which is responsible for turning the refrigerant gas into a liquid. That liquid is now transferred to the interior unit and is used to create cool air. After the process of turning from a gas to a liquid, the system then changes the liquid back into gas vapors and those vapors are transported (or sucked back) back to the exterior unit removing all heat before entering the compressor. And the process starts all over again, cycling the same refrigerant over and over again.
The A/C Suction Line and Insulation
Insulation on the suction line is a vital component of the air conditioning unit. The suction line must be well insulated to protect against condensation and keep the line cold. Otherwise, the cooling process becomes interrupted.
The line labeled as “FREON IS GAS” is the suction line.
Why is insulation vital to the operation of the A/C unit suction line?
To avoid condensation buildup
To keep heat out of the compressor
To reduce energy waste within the compressor
What does this mean for your A/C unit’s overall performance?
When the compressor is overworked because heat is able to enter the compressor it can increase the workload on the compressor. This can reduce the life expectancy of the compressor and increase energy consumption which can increase repair costs and energy bills. Recall, the insulation on the suction line is what eliminates the transfer of heat to the compressor.
What costs can be associated with A/C suction line replacement and repair?
It is far more efficient and affordable to replace or repair the insulation for the suction line than it is to replace or repair the compressor. Why delay a simple repair of less than $100 that’ll protect the life expectancy of the compressor, which can cost up to $1,000, or more.
Fun Fact About Your A/C!
You should never have to add refrigerant to your A/C unit because it never “uses up” refrigerant. However, if there is a leak, the system will have to be recharged.
SOURCES:
https://www.trane.com/residential/en/resources/hvac-basics/how-does-an-air-conditioner-work/
https://www.carrier.com/residential/en/us/products/air-conditioners/how-do-air-conditioners-work/
