What’s Wrong With My Car’s Air Conditioner?

By Cam Benty 03/01/2021 11:30am

Check out these tips on what to look for when your air conditioning fails you because everyone wants to keep their cool on a hot day.

Whether you crank your A/C to high but can’t get any relief, no air seems to flow out of the vents or a blast of heat just won’t quit, find out what’s wrong with your cooling system.

The culprit may be a cooling system leak in the system or worse.

Start with the Air Conditioner Fan

If there’s no cool air coming out of your dash, check to see if the blower is working. Turn the fan on high and make sure the dash vents are open. Also, make sure the air conditioner button is on.

Hot air coming out of the vents is a sign that the fan is working. No airflow means the fan itself or its fuse is blown. Another problem could be a plugged cabin filter, especially if you haven’t had it cleaned or replaced in a while.

A Question of Cooling

Next, check whether or not the air flowing out of the vents begins to cool. If it doesn’t, it could mean a problem with the air conditioner’s condenser. This component is a radiator usually mounted in front of the engine’s main cooling core.

The condenser transfers heat from the air conditioning system and cools the air coming into the cabin. Make sure there’s nothing blocking it. If there’s dirt or other debris, you can clean the surface using a blast of water, but don’t try to use a brush or other tool to scrape the surface because you can damage the cooling fins.

Check the Air Conditioner Refrigerant

The refrigerant is used to help cool cabin intake air and transfer heat from inside your vehicle. An engine-driven compressor pressurizes and circulates the refrigerant, which flows through tubes to the climate control core in the vehicle and out the condenser in front of the radiator.

If you have too much or too little refrigerant, your air conditioning won’t work. No refrigerant, which also includes lubricating oil, can damage the compressor. Most A/C systems have safety switches that will prevent the compressor from engaging if the charge is low or empty.

Modern autos use either R134a or 1234yf refrigerants to avoid the negative environmental impact that older chlorofluorocarbons had on the ozone layer. All cars since 1994 have systems that use these newer formulas.

If your vehicle is older than 1990, check with an expert about bringing your vehicle up to spec because the new refrigerants (and corresponding refrigerant oil) will not be compatible.

Look Over the Compressor and its Connections

With your engine idling, turn on the air conditioning full blast and look at the A/C compressor, which generally attaches to the front of the engine.

It is belt driven. If it’s not turning, you may have a seized compressor that needs to be replaced. If it is turning, look at the front of the compressor to watch the clutch mechanism. It should click on and off from time to time as it pressurizes the A/C system. If it doesn’t engage (no noticeable click), then the clutch could be the culprit.

Also, inspect the metal (silver) and rubber (black) hoses that attach to the back of the compressor and route through the engine compartment for evidence of leaks. The lubricating oil that circulates through the system with the refrigerant might cause dirt to build up around a joint, indicating a leak.

When to Call Professionals

An important note: Adding refrigerant can be dangerous and damage the air conditioner if you don’t know what you’re doing. Modern A/C systems are charged by weight (the exact amount is specified on a tag usually affixed to the core support) with a quality scale or charging station.

Unlike adding engine oil or brake fluid, recharging an air conditioning system is a job best left to automotive professionals.