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What Is The A/C Pressure Switch And Why Is It Important?

An air conditioner (A/C) pressure switch is an important part of a Volkswagen vehicle's cooling system. It's not as well-known as other parts like the compressor or condenser. Yet, it still plays an essential role in keeping the system functional.

What Is An A/C Pressure Switch?

vw ac pressure switch

An A/C pressure switch is a temperature-sensitive safety switch. Each vehicle has two A/C pressure switches:

  1. One A/C pressure switch mounted on the upper side of the A/C system (low pressure side)
  2. One A/C pressure switch mounted on the lower side of the A/C system (high pressure side)

If the refrigerant pressure rises above or drops below certain points, the A/C pressure switch turns off the compressor.

Why Are A/C Pressure Switches Important?

Though small in size and simple in design, this component plays a crucial role in protecting the compressor from wear and damage.

When the refrigerant pressure gets too high, the compressor can overheat. When the refrigerant pressure gets too low, the compressor can get damaged due to low oil.

Both of these conditions can lead to compressor failure and high repair costs. This is why it's important to check the switch when inspecting any strange temperature-related problems.

Signs Of A Failing A/C Pressure Switch

Replace ac pressure switch

Image Credit: DIYEthan

There are several signs that may indicate the need for an A/C pressure switch replacement:

  • A/C system not turning on
  • A/C system not blowing cold air
  • A/C system functioning intermittently

In some cases, when an A/C switch fails, the compressor ends up being vulnerable to the refrigerant pressure and may fail as a result. In other cases, when the A/C switch fails, the still-functioning compressor won't turn on. Either way, the compressor won't work. Therefore your A/C system stops working.

As soon as you notice issues with your Volkswagen's A/C system, check the compressor and A/C pressure switch ASAP.

How To Confirm That One Of Your A/C Pressure Switches Has Failed

Image Credit: golfWagen

One of the best ways to confirm a failing A/C pressure switch is to use an Onboard Diagnosis System (OBD). The error code(s) can tell you a lot about what's going on with your A/C system. The following are some of the most frequent OBD error codes linked to a bad AC pressure switch:

  • P0745: Pressure control solenoid malfunction
  • P0746: Pressure control solenoid performance or stuck off
  • P0747: pressure control solenoid stuck on
  • P0748: pressure control solenoid electrical (this may indicate an issue with the electrical wiring for the switch)
  • P0749: Pressure control solenoid intermittent

The following codes may mean that there’s an issue with the switch or another component of the A/C system:

  • P0530: A/C refrigerant pressure sensor circuit malfunction
  • P0531: A/C refrigerant pressure sensor circuit range/performance
  • P0532: A/C refrigerant pressure sensor circuit low input
  • P0533: A/C refrigerant pressure sensor circuit high input

If you have some knowledge of your Volkswagen's A/C system, you may be able to replace the faulty A/C pressure switch yourself. Most dealerships will charge high labor costs just to install a $30 switch. So you'll save a lot of money by taking care of the job yourself.

Be sure to find a good model-specific tutorial to follow. You may find one on YouTube, for example.