How to Find the Low-Pressure Side of an AC Unit on a Car

by Anthony Smith
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The air conditioner on a car is designed as a closed, pressurized system. The system consists of a high-pressure and a low-pressure side. When servicing the air conditioner, it is very important to be able to distinguish between the two. Whether simply adding refrigerant to the system, or doing more extensive work, there is a simple method that will enable you to find the low-pressure side of the car's air conditioner.

Step 1

Open the hood of the car and secure it.

Step 2

Locate the air conditioner compressor. It is one of the units that are powered by the engine's belts. It will have stainless steel tubing running to and from it (this may be covered by a sheath), and this tubing will be of a larger diameter than those running to the power steering unit and the alternator, the two other belt-powered units.

Step 3

Locate the receiver dryer. This can be identified as a canister-shaped unit that is connected to the compressor by tubing. Follow the tubing from the compressor until you find it.

Step 4

Find the low-pressure side of the AC unit using a process of elimination. The side of the AC that leads from the compressor to the receiver dryer is the high-pressure side, so the piping leading from the compressor to the opposite side will be on the low-pressure side.

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