What's Wrong With My A/C?

By P Sanchez

​Driving in a hot and humid day without air-conditioning is the pits. The prospect of sweating it out in your car will make you seriously consider your ridesharing options or ditching your commuting plans altogether. That's why having a good climate control system is more than a perk, it's a must-have. 

It’s important that car owners are keenly aware of the performance of your A/C system and knowing when it’s time to take your car to a car a/c repair specialists. Let’s look at a few common complaints about troubled A/C systems and get an idea of the possible reasons why they happen.

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Weak Airflow

There are several reasons why your A/C is not blowing air is strong as it does before. The simplest reason could just be a dirty filter. The cabin filter captures airborne particulates as air enters the a/c’s airbox (not to be confused with the engine’s air filter and airbox) which houses the evaporator. The filter can clog up with dust and dirt over time. 

Filters are cheap and inspecting or replacing the cabin filter can be a completely doable DIY project. However, the ease (or difficulty, depending on how you see it) of doing so will differ with every car make and model. That said, most cabin filters can be accessed from behind the glove-box. Some disassembly will be required.

The cabin filter is probably the only component of a car A/C that’s DIY serviceable, every trouble moving forward will need servicing from specially trained technicians with specialized equipment. 

Clogging can also happen with the evaporator itself. The evaporator creates a lot of water condensation which promotes the growth of molds and mildew on the evaporator’s surface which can impede airflow. 

Another reason for weak airflow can be cracked, damaged and/or misalignment of the plastic passageways for the air. Vents can also get clogged with small foreign materials like pieces of foam, paper tissue, coins, and so on.

Maybe your A/C is not effectively drawing in air from the cabin. This could be an issue with the centrifugal fan (it’s squirrel cage looking plastic part) and the electric motor. Lost of airflow, sometimes accompanied by a burnt plastic smell, is a telltale sign of a fried motor.

It’s Blowing Air But The Air Is Not Cold

Noticing that the air from your A/C is getting less cold even when you’ve cranked the dials? It’s likely that your system is leaking Freon, probably the most common A/C problem cars that cars develop. Seals, o-rings and rubber tubings can get brittle and degrade over time. The metal tubings can resist external corrosion but are not completely impervious. Corrosion can also happen internally like when the refrigerant and moisture react creating corrosive byproduct. 

While we’re on the subject, absorbing moisture from the Freon is the receiving dryer’s job but usually, after 3 years of continued use, the desiccant pellets within will already be saturated, at which point the dryer needs to be replaced.

Mechanical forces can also fracture or perforate the tubings which will cause leaking. If your car has figured in a front-end collision, even in a slow speed one, then the integrity of the condenser is already in question. 

If it’s not a leak, it could be clogging at some point. A malfunction with the expansion valve can cause clogging or incorrect flow of Freon. To test for leaks and internal clogs, A/C technicians use a special A/C pressure tester as well as UV dyes to isolate and locate the problem.

Issues with the compressor can also cause a non-cooling scenario. It could be an electronic failure like a bad fuse, switch or relay. Or it could be the control module at fault. It could be an electrical issue preventing the compressor from engaging, such as the electromagnetic clutch burning-out. The compressor itself can go bad. It can seize because of loss of internal lubrication, or simply bite the dust because of age.

Conclusion

Like any part of your car, the service life of your A/C system will be prolonged by regular preventive maintenance. Finding issues early and promptly fixing them helps avoid costlier repairs down the road. Check with your owner’s manual and see how often you should take your car to an air-conditioning specialist at your nearest auto repair shop.