AC Low-side pressure too high: causes and how to fix 

What can actually cause the AC low-side pressure to get too high? Auto air conditioning systems commonly experience high-pressure buildup on the low side. But it’s a circumstance you want to avoid, especially in the hot summer. The interior temperature rises to a point where it is uncomfortable on a sunny day when the AC pressure is too high. The unit is slowly being ruined, and this situation indicates that there is a deeper problem.

AC Low-side pressure switch too high

When AC low-side pressure rises too high, the system will be unable to produce the necessary temperature to cool the car. There are numerous possibilities that could apply to this case. It might have to do with the compressor, the refrigerant used to charge the air conditioner or even a system leak. Today, you’ll get to know the causes, testing, and how to fix the AC low-side pressure too high issue.

Read more: Understanding AC pressure switch

Let’s get to it!


What causes the AC low-side pressure to get too high?

Here are some of the things that can cause the AC low-side pressure to get too high:

A failing AC compressor

It is often the compressor’s fault if the low-side pressure is too high and the high-side pressure is low. Even when the AC system is turned on, you won’t get cold air because the refrigerant can never circulate without the compressor. This typically occurs if your AC system is not used for an extended period of time.

Read more: Understanding an Air Conditioning System

Overcharged AC

The system might simply be overcharged. Even with the engine off, you will notice high pressure. Either too much oil is present or there is too much refrigerant in the air conditioning system. In either case, until you relieve some of that pressure, which is something that should ideally be done by a mechanic, the issue won’t go away on its own.

Read more: List of best quietest window air conditioner

Damaged condenser fan

Airflow through the condenser is reduced when the fan is damaged. It’s also possible that some of the airflows are being obstructed by debris, which would result in the same issue. A leak could develop as a result of the fan problems, in addition to warm air blowing out.

Damage will undoubtedly result from the low-pressure side’s inability to withstand these greater pressures, possibly even to the point of causing an evaporator coil leak. If this occurs, the air conditioning system will be seriously damaged and will need additional repairs.

Read more: Understanding AC condenser fan

Testing the AC pressure

If you have a good set of gauges, testing the AC pressures is not difficult. Additionally, you should be aware of the recommended pressures for your vehicle, which may be found in the service manual. The car’s specifications can be found online if you don’t have the service manual close at hand.

Attach the pressure gauges for the AC. The AC system has two caps that you can see. Two caps are present: one for the side with low pressure and the other for the side with high pressure. When compared to the other side, the diameter of the high-pressure side is smaller.

If you ever have any questions about which cap is on which side, the service manual contains a detailed map. Finding the ports can be difficult depending on the type of vehicle you drive because they are frequently hidden under other components, sometimes even the engine block.

Your gauge will use a color-coding system to help you see the various sides. Blue is used for low pressure, and red is utilized for high pressure. Once the gauges are linked, start the engine of your car. Give it a few minutes to run so that the refrigerant can flow and you can get an accurate reading.

Analyze the reading and inspect the gauges. The low-pressure blue gauge should read between 25 and 30 PSI if everything is operating appropriately. On the other hand, a typical high-pressure setting is often between 200 and 250 PSI.

Remember that these summaries are merely estimations. The service manual for your vehicle may have different requirements. It is obvious that there is an issue if the pressure on one side is excessively low or high. In order to prevent more harm, you should have the system examined as soon as possible.

Read more: 4 signs that your car’s air conditioner needs freon

How to fix the AC low side pressure too high issue

There are a lot of things that can cause the AC’s low-side pressure to get too high. One of the causes of an AC low-side pressure that is too high can be a damaged or leaking evaporator coil. Replacing the damaged or leaking evaporator coil can resolve the AC low-side pressure too-high issue. However, depending on the model of the car and the mechanic’s hourly rates, an evaporator replacement might cost anywhere from $850 to $1100 for parts and labor.

An overcharged AC system can cause the low-side pressure to get too hot. A mechanic would normally utilize a device that uses vacuums to discharge or bleed excess refrigerant from the AC to fix an overcharged AC system. The device will monitor pressure levels while it operates, and if they return to normal ranges, your mechanic will be able to determine that the AC system once again has an adequate amount of refrigerant. The extra coolant is kept in the machine so it can be utilized again later.

You should take care of your car’s AC system right away if it is overcharged or contains too much refrigerant. Contrary to expectations, having too much refrigerant in your car’s air conditioning system can lead to excessive heat and pressure, which may be the cause of your AC system blowing hot air out of your vent right now. An overcharged air conditioning system in your vehicle can damage the compressor if it isn’t fixed.

However, we discussed that the issue can also be the result of a damaged condenser fan. So an AC condenser fan replacement typically costs between $300 and $425. Labor costs can range from $55 to $200 depending on your make and model, while parts might cost between $245 and $330.

Watch the video below to learn more about AC low side pressure too high issue:

Read more: Lists of Best Portable Air Compressors


What happens if the car’s AC pressure is too high?

The energy in the AC compressor may cause the pressure in the car to become excessive. The evaporator has the potential to burst out and leak.

What causes the high-pressure switch on the AC?

In the winter, a lack of airflow across the indoor coil is the most frequent reason for a refrigerant high-pressure switch to trip. Having a high temperature split throughout the indoor coil is one indication that there isn’t enough ventilation. Check the filter for restrictions in addition to just dirt.

What causes the low-side AC pressure to be too high and the high-side pressure to be too low?

This problem could be caused by a number of things, including problems with the heater or AC controls, low refrigerant levels, compressor problems, and more. Low-side high and high-side low pressure in the air conditioner is one sign of an air-conditioning problem.

What are the symptoms of an overcharged AC system in a car?

  • A lack of cooling or warm air is flowing from the vents.
  • The compressor is noisy or not working.
  • High-pressure reading.
  • Engine failure.

Can you drive with an overcharged AC?

You can expect your air conditioning system to not function effectively if there is air present and Freon is added. The compressor experiences significantly more strain when you drive your vehicle with an overcharged AC system. It may even harm the system in the long run.

Will an overcharged system not cool down?

One major issue is that too much refrigerant prevents a proper transition between the liquid and gaseous states, causing more of it to remain in the liquid form. This will reduce the system’s effectiveness and have an impact on the cabin’s cooling.

What should the AC pressure be with the engine running?

The system should have a low pressure of 25 to 30 psi and a high pressure of 200 to 250 psi. The pressures will change in accordance with changes in the ambient temperature (70 to 80 °F), which may be greater or lower than usual.

What happens if you put too much r-134a in the system?

Your AC compressor may become damaged if it contains too much refrigerant. This may occur because the extra refrigerant will probably gather inside the compressor and result in subcooling, which lowers temperatures more than normal. Additionally, the extra refrigerant has the potential to flood the compressor and harm its mechanical components.

Will low refrigerant cause high pressure?

The compressor will make an effort to draw refrigerant into its cylinders, but there won’t be enough to fill them, resulting in low pressure over the entire low side of the system.

That is all for this article, where we discussed the causes, testing, and how to fix the AC low-side pressure too high issue. I hope you learn a lot from reading this article. If you do, kindly share it with others. Thanks for reading; see you around!