With another winter receding into the past, you'll soon need to start using your car's air conditioner again. If you live in one of the warmer parts of the country, temperatures may already be high enough to roll up your windows and enjoy the cool comforts of the air conditioner. Of course, it's frustrating when the only thing that greets you from your vents is warm, stale air.

There are plenty of potential causes for an AC system that refuses to keep your car cool, but a failed pressure switch is a relatively common (and inexpensive!) failure point. Keep reading to learn how this tiny component can keep you from enjoying a cold cabin and why you shouldn't try to bypass a faulty switch.

How Pressure Affects Your Compressor

Your car's air conditioner is a bit like Goldilocks: it needs the refrigerant pressure to be just right. If the pressure is too low or too high, the compressor will struggle, potentially overheat, and may even fail. Low pressure can be particularly problematic since it may allow liquid refrigerant to return to the compressor, creating a harmful situation known as "slugging."

All air conditioning systems contain high-pressure and low-pressure switches to help avoid refrigerant pressure problems. These switches also affect the routine operation of the system since pressure on both sides will vary as the system runs. On most cars, the low-pressure switch must close for the compressor clutch to engage and the air conditioning to start.

Why a Faulty Switch Affects Your AC

Switches typically fail in a "safe" position that prevents the AC from running. This design ensures that a relatively inexpensive pressure switch failure won't result in far more costly compressor damage. A bad switch may prevent your car's air conditioner from turning on at all, or it may result in short-cycling that allows the AC system to run briefly.

While it may be possible to bypass a pressure switch by shorting the contacts, you should never attempt to solve your problem this way. Both the high and low-side pressure switches are critical safety devices for your car's compressor, and bypassing them can result in severe damage. Since compressor replacements can be expensive, it's never worthwhile to take this approach.

What You Should Do About Pressure Switch Issues

If your AC system won't run at all or you notice short cycling behavior, you should stop using it and take your car to a qualified AC repair shop. These problems can have numerous causes, and a trained technician can help determine if a faulty pressure switch is to blame. By bringing your vehicle to a professional car air conditioning service, you'll ensure you get a permanent fix that won't risk damaging your AC compressor.