Overcharged AC System: Learn the 7 most common symptoms

Learn the seven symptoms of an overcharged AC system

Many DIYers think adding more refrigerant will give them better cooling when recharging their vehicle’s air conditioning system. However, this is incorrect. R-134a refrigerant has a narrow tolerance for over and undercharging, and an overcharged AC system reduces your AC’s cooling capacity. In other words, overcharging your car’s AC system is counterproductive. How can you tell if you’ve gone overboard with the refrigerant? Here are the five most common symptoms of an overcharged AC system.

1. Warm air from the vents

An overcharged system floods the evaporator with liquid refrigerant, preventing it from turning into a vapor to remove heat from the cabin. So you don’t get cold air.

2. An overcharged AC system has extremely high pressures

The AC gauges show excessively high pressures on both the high and low sides.

3. An overcharged AC system causes leaks from seals and joints

The high pressure can cause weak points or old components to fail and start leaking. If you recently added too much refrigerant and now have leaks, overcharging is likely the cause.

4. Squealing Compressor

Too much refrigerant leads to extremely high pressures that make it very difficult for the compressor to start, causing the clutch or belt to squeal.

5. The compressor can be damaged from slugging

Normally only refrigerant vapor enters the compressor. But when overcharged, liquid refrigerant can enter, potentially causing a hydraulic lock and catastrophic compressor damage.

6. The Relief Valve Opens To Blow Off Excess Refrigerant

In cases of extreme overcharging, the pressure relief valve may open to release some refrigerant and prevent the system from bursting.

7. Reduced Fuel Economy

This is an example of extremely high pressure on the high side of the system.

The AC system has to work harder to overcome the high head pressures when overcharged, consuming more energy and resulting in lower fuel mileage than normal.

To avoid these issues, it’s essential to charge the AC system to the manufacturer’s recommended levels and ensure regular professional servicing. If you suspect your system might be overcharged, promptly address the issue to prevent further complications.

For more information on AC overcharging, see this video.

For more information on the most common causes of AC compressor failure, see this article.

©, 2023 Rick Muscoplat