Auto Repair Tips & Advice > Fluids, Heat & Air Conditioning

Is there any way I can tell if my air conditioner needs refrigerant?

There are several ways to determine if your air conditioner is low on refrigerant.

Poor cooling. If your air conditioner isn’t putting out much cold air, it could be low on refrigerant. But an A/C system can still produce cool air even if it’s lost up to 50% of its original charge of refrigerant. Even so, output will be reduced. If the system is working properly, it should blow air that is approximately 50 degrees cooler than the ambient air temperature.

Poor cooling, however, doesn’t necessarily mean the refrigerant is low. You might have another kind of problem. So to determine the cause, the system should be diagnosed by a skilled professional who understands air conditioning.

If your A/C system has a "sight glass" (a small round glass window usually located on or near the receiver/drier or accumulator), you can "see" inside the system. Refrigerant is clear so it’s hard to tell if the system is full or empty.

If the glass looks clear and there is no cold air output, the system has lost its charge of refrigerant through a leak somewhere in the system. If you see bubbles or foam in the sight glass, it means the system is low on refrigerant and needs to be recharged.

The most accurate means of determining the refrigerant level in your A/C system is with a set of A/C gauges. The gauges will show how much pressure is in the high and low sides of the system. The pressure specs vary from application to application, but generally speaking a high side reading of less than 160 lbs. at 80 degrees F, and/or a low side reading of less than 16 to 22 lbs. at 80 degrees F indicate a need for additional refrigerant.

If you see oily streaks radiating outward around the compressor shaft seal, or wet oily areas around hose connections, it means refrigerant is leaking from your system. This too, may indicate a need for additional refrigerant to replace that which has been lost.

Most A/C systems leak a little refrigerant over time. Newer systems are tighter and leak less than older ones, which may lose up to several ounces of refrigerant a year. After five or six years of service, therefore, it’s not unusual for the system to need some additional refrigerant.

If your A/C system can’t hold a charge from one season until the next, it has a major leak that should be pinpointed and repaired. The type of refrigerant (R12) used in all vehicles built prior to 1993 causes damage to the Earth’s protective ozone layer. So leaks should be repaired to prevent the loss of refrigerant.

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Is there any way I can tell if my air conditioner needs refrigerant?