Any vehicle that has air conditioning is going to have an air conditioner pressure switch. The purpose of this part is to monitor the refrigerant pressure in the air conditioner system. If the pressure gets too low or high, the pressure switch cuts off the compressor so that it doesn't become damaged.

Here are some signs that you could have a problem with your pressure switch. 

Engine Light  

One of the first warning signs you may see is a check engine light on your dashboard. Even though your air conditioner is not part of the engine, the pressure switch can trigger an error code that turns this light on. You can then have the code read by an auto parts store or a mechanic to determine what part is failing.

If the air conditioner pressure switch is the problem, you may get an error code such as P0530, which means there is a problem directly related to the pressure sensor circuit. Error code P0533 indicates that the pressure within the air conditioner is too high. 

Inactive Compressor

It's possible for the compressor switch to malfunction without setting off a warning light. Since the pressure switch has the job of turning off the compressor when pressure is too high or too low, you may notice that the compressor is not turning on at all. This is because the pressure switch is getting a faulty reading and shutting off the compressor, even though the pressure is completely fine. You'll need to have the pressure switch repaired or replaced to ensure that it is not a problem with high and low pressure. 

Warm Air

If the air conditioner pressure sensor is shutting down the compressor, then you will likely have warm air blowing through the vents. Without the compressor being able to engage, the refrigerant is not pumping through your vehicle's air conditioner system. The fans will still spin to move the air through the vents, but it is only going to move warm air.

Be aware that warm air can indicate a problem with a lack of refrigerant as well. This is likely the first thing that a mechanic will check before they investigate the pressure switch because low refrigerant is much more common due to having a leak. 

Inconsistent Cold Air

Have you noticed that the air conditioner works some days and doesn't work on other days? This is likely due to the pressure switch being faulty and giving incorrect readings. If the problem was related to low refrigerant, then it would consistently blow hot air. 

For help with car repairs, contact a company like The Brake Shop.