Why is AC Pressure Too High in Your Car?

The AC plays an essential role in keeping the interior temperature of your car under control. Therefore, if its Pressure is too high, it could be a sign of underlying problems such as diminishing or leakage of coolant, which call for immediate attention.

Significance of AC Reading​

It is essential to examine both the low as well as high reading of the AC. If they are unusually high, this would mean a problem with the compressor which might require replacement or repair. Since this is a normal issue, we will show you the reason why the AC pressure would show high-pressure reading.

The higher than usual temperature reading in an independent test might be only the beginning. This result is damaging as the compressor is made to operate within a particular range. High pressure would gradually result in the failure of the compressor, which can cost you a lot of money for repairing if not solved in time.

AC Pressure Problems​

A high amount of pressure inside a compressor would make the evaporator to leak and the aluminum to distort. Also, the cost of replacement as well as repair of a compressor is expensive as removing the dash for rectification.

In general, higher than usual air pressure is often a result of two situations. The fist one is that the AC system in your car would face no or limited flow of air via the condenser, which might be the consequence of a broken condenser fan motor. The same problem would also happen if debris exists near the fan and blocks the flow. Another common cause for a reading with high pressure could be the overcharge of the system.​

Issues With Condenser Fan

The condenser fan in a coolant system would work at different capacities and speeds. Therefore, a malfunction would reduce its pace along with efficiency. In turn, this will result in the inability of this part to cool the system effectively and pass airflow. You could check and find out any problems easily with any DIY equipment.

AV System Errors​

An excessive amount of refrigerant or coolant and oil in the system is often the cause of overcharging problem. To test the overcharge, you might need to take the content of your system and determine instead of putting more coolant to it.

To prevent this problem from occurring, you would apply a leak test kit to find out any leakage at the bottom. Do not let any airline open because it would lead to the coming flow of air, which causes high-pressure reading. Also, you need to make contents in oil of different components during the process of replacing and repairing.

These days, most of the car models are made with an R134a AC system. Thus, the following tips we suggest have been applied for R134a AC system and would be helpful in other cooling systems as well.

​The two reasons mentioned above would help you figure out what is going wrong with the AC system in your car. Nevertheless, the application of incorrect compressor lubricant can also lead to this problem in a coolant system. To get a more specific diagnosis, you should check either the high side as well as the low side pressure reading.

  • When both measurements are high, along with bubbles in the system, you should remove all of the refrigerants.
  • Bleed out the coolant until you notice a heavy stream of bubbles. After that, recharge with refrigerant till the bubbles in the glass go away.
  • If only high side reading is high, you might need to get rid of the refrigerant.
  • Another way to solve this problem is to replace the dryer and recharge.

Before doing this, however, you need to make sure that the readings of the low side are consistent over time.

System Restrictions and Blockage

If the system of your car has a restriction or blockage, the reading of the high side might be high while the low one could reduce over time. To deal with this issue, you have to remove the parts and clear the restriction or debris. After that, check these measurements again. If the problem persists, have your car repaired immediately by a professional mechanic.

In general, it is not common to have a high reading with low side pressure reading and the normal one with high side. If you are dealing with this issue, it would be because the compressor is cycling incorrectly. In other words, the cycles are moving out and in too quickly, which cause these high readings at the low side. You would not be able to solve this malfunction yourself.

A high low side reading (with usual high side reading) is often the result of a malfunction in the thermostat switch. Therefore, you should get this part replaced or checked by an experienced mechanic.

A common mistake that many amateur mechanics would make is putting too much refrigerant into the system without removing their systems first. In fact, this action is not helpful for the diagnosis and would make the situation worse for a compressor.

In these situations, we advise you to take it carefully and slowly. Take your time and think about different steps instead of making a terrible mistake. If everything seems out of control, immediately call for your mechanic.​

John Henry

I am John Henry and I have begun to work in automotive industry since the 90s, specializing in car rebuilding and repair. After nearly two decades of working in this complex section, with extensive experience in repairing, troubleshooting and maintaining thousands of cars, I started to work as an auto blogger to share my practical knowledge as well as skills with car owners all around the world through a wide range of articles in online magazine.

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