VW AC Not Working

The hot seasons will be here before you know it, and now is the time to deal with a VW A/C that’s not working. Here is an easy guide to understanding what causes A/C issues and how you can fix them yourself.

What is an Automotive A/C System?

It’s important to understand what your Volkswagen A/C actually is. In very basic terms, it’s a refrigerator with an odd layout. Here’s what the system is made up of:

  • Compressor: The compressor pressurizes your systems refrigerant, which both circulates it throughout the system and allows it to release heat in the condenser. The compressor is the critical component in most A/C systems, and also the portion of the system most likely to fail.
  • Condenser: The condenser is the part that allows the refrigerant to change from a gas to a liquid, releasing heat in the process. This heat is released to the surrounding air outside the vehicle.
  • Refrigerant: This substance is known as R-134a on modern cars (and R-12 freon on older models) and is designed to carry heat away from your vehicles climate control system, thus cooling your car.
  • Expansion valve/orifice tube: This nozzle causes the refrigerant pressure to drop, while simultaneously causing the refrigerant to atomize. This valve meters flow as well.
  • Receiver/dryer: This element acts as a filter for the refrigerant and removes moisture and contaminants from it.
  • Evaporator: The evaporator absorbs heat from the air in your vehicle, thereby cooling it. Once the refrigerant leaves the evaporator, goes back thru the expansion valve, and then into the compressor. The cycle is complete.

Then there’s lines, wiring, sensors, and fuses in the mix as well. So, it’s a pretty involved system where many different things could go wrong.

The Diagnostic Process

Identifying the problem is larger a process of elimination to pin-point the issues.

Here are the steps (in as painless order as possible):

  1. First, do a visual inspection for damage to switches, broken/bad fuses, frayed wires, a broken fan belt, or damage to the compressor.
  2. Check for refrigerant leaks, which are easy to spot but hard to fix. Purchase a dye kit form your local auto parts store to add to the system — the kit will come with more detailed instructions, but it will basically light up the area of the leak (if one exists).
  3. If the A/C is on and blower is on, the clutch might not be engaging. Crank the car, turn the air conditioner on, and look under the hood. Locate the compressor and check that the outer pulley and inner hub are turning to signify that the clutch is engaged. If not, this may be the result of a wiring problem, a bad fuse, a broken A/C switch, or low refrigerant.
  4. Note the level of cooling as well. If the system is cooling, but not enough, it might have low pressure and needs to be topped off with refrigerant.

Additional Tips

  • Leaks in the system can allow moisture to enter — which can lead to very poor performance.
  • Too much refrigerant in your Volkswagen will actually decrease the performance of the car until the level is adequate — do no overfill!
  • Certain kinds of refrigerants are illegal in some U.S. states — such as HC12a.
  • Heat from your engine may also cause the system to struggle to cool, insolation/heat wrap can help this issue.

If the problem with your A/C system isn’t evident, than it might be time to bring it to a service shop or your local VW dealer. Just remember, we have OEM VW A/C parts at wholesale prices, and we deliver!