Updated at: 20-05-2022 - By: Lucas

If you trust your air conditioner’s compressor, it’s working at its best.

But since it is a part of refrigeration, it can also go wrong.

If something like this happens, you will need to know how to read the A/C compressor unit.

Someone with the right training can do that job for you. The technician should know about the A/C compressor and have the right tools.

The pressure chart is a piece of information that is needed. A/C compressor unit problems can be found by looking at the pressure chart.

In this article, we will look at an R134a low side pressure chart, which is a type of pressure chart.

Read on if you want to find out what an R134a low-pressure chart is.

Before we talk about what the R134a low side pressure chart is, let’s talk about what R134a means.


What does R134a mean?

R134a is a coolant that is used in a wide range of home and commercial appliances. The compressor is a cooling unit that comes with these home appliances.

The R134a refrigerant is inside this compressor. The refrigerant makes it possible for the compressor to work well.

Putting a gauge or metre on this part helps you understand how it normally works.

The metre shows the pressure readings along with the refrigerant temperature readings. In this case, the refrigerant is R134a.

On a table with three columns, these readings are written down. We have the low side column for temperature and the high side column for pressure.

The table is usually called the pressure chart. Since the refrigerant in this case is R134a, we will use the R134a pressure chart.

The R134a pressure chart shows the relationship between pressure and temperature for R134a refrigerant.

There are two kinds of the r134a chart,

What is a R134a Low Side Pressure Chart?

r134a low side pressure chart-1

R134a pressure chart for the high side.

The gauge or metre on the refrigeration part has two metres or gauges in it. We have a gauge for low pressure and one for high pressure.

The readings for the low side pressure chart come from the low side metre. In the same way, the pressure readings on the high side pressure chart come from the high side gauge or metre.


What is a chart for R134a low side pressure?

It is a chart that shows how pressure and temperature are related on the lower side of the air conditioner compressor.

How to Read an R134a low Side Pressure Chart


The technician uses this chart to decide if the A/C compressor needs a refrigerant recharge.

In the same way, it tells you if the compressor needs to be changed. So, it shows how well the A/C compressor system is working.

The R134a low side pressure chart is used by the technician to make sure that the A/C compressor unit is working at its best.

It’s hard to figure out what the R134a low side pressure chart is. In the same way, it is never easy to figure out what the numbers on the charts mean. Don’t forget that this measure is against pressure.

So, you need to know what each reading means.

When figuring out what this reading means, you look at both the low and high sides of the chart. But this article is about the pressure chart for the R131a low side.

So, let’s pay attention to the low readings. Remember that we are comparing the pressure readings to the temperatures.

How to Read an R134a Low Side Pressure Chart

Well, let me show you how everything works.

Remember this: if a compressor is working well, the low side pressure chart should show low readings.

It will show that the compressor is clean and that the air flow is at its highest level.

This method will teach you how to read the numbers on the r134a low-pressure chart.

On the low end, the temperature is high but the pressure is low. You should see two things from it.

The air conditioner’s compressor system is not running. So, its operation involves a changing displacement.

There could be a problem with how the compressor works. So you need to find another one to replace it.

When the low side of the chart has a lot of pressure, check the following.

Check the fan in the condenser. It could not be going. Air can’t get through because the dirt is blocking the holes.

There could also be something blocking the flow of refrigerant in the compressor.

On the bottom of the chart, where the pressure is low and the temperature is high, the wind speed is high. It should mean that the system isn’t working at its best.

When you look at the R134a pressure chart, you’ll see that the pressure on both sides is almost the same. Think about what follows.

The function for moving the AC compressor isn’t working, so it needs to be checked.

The A/C might not be working because the expansion valve is stuck.

In other words, the air conditioner’s compressor could be broken inside.

Hold on, I know you’re probably wondering and asking yourself,

What are the Normal Operating Pressures for R134a?

The normal pressure for an R134a is between 22 and 57 pounds per square inch (PSI).

Remember that the chart has two sides: the low and the high.

So, the low-pressure side of a normal R134a should be at 90 degrees or less, and the PSI should be close to 30.

After reading all of the above, you may still be wondering,

Why Is my Low Side AC Pressure High?

r134a low side pressure chart

As I said in the part about how to understand the reading, which was point number two, above.

High pressure on the bottom of the pressure chart is not a good sign. In other words, your appliance’s air conditioner compressor unit could be broken, so it needs to be serviced.

When the technician looks more closely, he or she should be able to see the following:

The condenser fan might not be running because dirt is getting in the way. So there is something in the way of the air flow.

The coolant might not be flowing right.

All of the above problems can be found by a qualified person with the right tools.


Every technician needs the r134a low-pressure chart. Whether it’s for home inspection and interpretation or commercial interpretation

The table makes it easier to look at, find, and solve problems that come up in the readings. If you’re a technician, you might want to keep it with you at all times.