What You Need to Know About Your Car’s AC: Repairing it, Maintaining it and Saving $

Well, it’s official. NOAA announced that July 2019 was the hottest July ever on record not only in the U.S. but globally. If you can’t stand the heat or your life seems to be ruled by Murphy’s Law (anything that can go wrong will go wrong), you’ll want to hear our tips on maintaining your car’s air conditioning for longevity and what to do when it starts to malfunction

When the AC system in your vehicle is blowing tepid air, cold air on one side and warm air on the other or the air smells a bit off, do you:
A) ignore it and roll down the windows or
B) go into panic mode about what needs repairing and how much it will cost

Chances are you fall into the latter category, and with good reason. AC system repairs can get pricey and they can be confusing if you don’t know how the system functions. Openbay is here to help you keep your cool. No pun intended.

Auto Air Conditioning 101

Most AC system repairs are a DIFM (Do it for Me) job, not a DIY. The way to tell the difference is by understanding how your car’s air conditioning works and which ancillary parts can be a DIY fix to save you a few bucks. Here’s our version of automotive air conditioning for “dummies” to get you started:

Refrigerant (a highly specialized gas) is the glue that holds the AC system together. AC generates cold air by converting refrigerant from warm, high-pressure liquid into cold, low pressure gas through four major components. If one of the four components malfunctions, it creates a ripple effect. Here’s the significance and repair scenarios for each component:

Compressor: When you turn on your car’s AC, the compressor sends the low pressure gas (refrigerant/Freon) through a high-pressure line to the condenser. The pulley on the compressor is in constant motion, even when the air conditioning system is not in use, and will wear out over time. The compressor also contains the most moving parts within the system, so breakdown at some point is expected. In newer cars with advanced climate control, sensor and computer problems are quite common. If a sensor stops working or if it measures incorrectly (either pressure or temperature) the system will stop working. If a compressor fails, and they can, you have an expensive repair on your hands. A seized compressor can break the serpentine belt and leave the car without a power steering pump, an alternator and a water pump.

Condenser: Located between the car’s grille and the engine cooling radiator, the condenser looks and acts like a small radiator. It receives the high-pressure gas from the compressor, then exposes it to the air entering from the grille (a small fan or two assists in this) and immediately converts the gaseous refrigerant to a high-pressure liquid. Essentially, the condenser condenses the refrigerant from a gas to a liquid. The liquid is then sent to an expansion valve.

Thermal expansion valve or orifice tube. The high-pressure liquid from the condenser is dispersed and becomes a cold, low-pressure gas.This drop in pressure creates a drop in temperature. The cold gas is released into an evaporator. 

Evaporator core. Before cold air makes its way through the vents inside the passenger cabin, it is pushed through the evaporator core. The cold gas from the expansion valve passes through the evaporator core to absorb the heat from the cabin air. The evaporator converts the cold gas to a liquid that recycles back to the compressor to start the process all over again.

This barely scratches the surface of the physics of your car’s AC, but for boredom’s sake we’ll stop there.

If Your AC is Acting Strange…

If the condenser is blocked or broken, the refrigerant will only reach ambient temperatures by the time it reaches your car’s cabin. You’ll notice that the AC is blowing hot/ambient air as a result. A compressor can get blocked or punctured by all sorts of road debris (leaves, trash, sticks, rocks, etc) since it’s located at the front of your vehicle. All you need to do is a quick visual inspection of the condenser by looking through the grille for debris or punctures. If there’s a puncture, replacement is likely your best option.

Broken cooling fans can also cause your car’s AC to blow hot air. The cooling fans could have a burnt out motor, chipped fan blade or an electrical problem. Other electrical faults, such as a bad connection or faulty sensor, can cause your car’s AC to stop working. If that’s the case, schedule an appointment with a trusted mechanic for a diagnosis.

The #1 Cause of AC System Problems 

Refrigerant is often referred to by the brand name Freon (like Kleenex for tissues), and if the refrigerant/Freon is low or has run out altogether, it’s time for an AC recharge. Not having a fully charged system is the number one cause of problems for most AC systems. 

As the air conditioning system ages, refrigerant will seep out through small leaks where parts are joined together and sealed with rubber o-rings (a circular gasket). These o-rings begin to dry out and cannot give an air tight seal. The system will still reduce temperature even with half the freon required, just not as well. Therefore as the car ages, a recharge of the system every three years is normal. If a recharge lasts only a short period of time, there is a more significant leak in the condenser or the evaporator, which needs to be diagnosed and repaired.

Recharge / Repair It

Topping off your AC with a can or two of refrigerant is not the way to go. An automotive technician is obligated by Federal law to find and repair any AC system leaks rather than simply adding more refrigerant as needed. Plus, new systems are quite intolerant of excess amounts of refrigerant onboard. Adding an entire 8-ounce can when the system is only an ounce or two low can actually damage the system.

Generally, when you bring in your car for an AC recharge, the technician will start by checking system pressures with his gauges. If the system is just a little low, he can start looking for leaks right away. If the system is too low or completely empty, refrigerant will have to be added to look for the leak. Once the source of the leak is uncovered, the auto tech will evacuate the system and repair the leak before refilling it.

A full AC recharge involves evacuating the old refrigerant and refilling it with new. This is the only way to determine if the correct amount is on board. If the system has been opened, or any components are changed, there’s an additional step. They’ll need to vacuum the system of all atmospheric air and moisture before charging it. Needless to say, this all takes a few hours, much longer than simply draining in a can of refrigerant without any diagnostics.

Click here to find out how much an AC recharge will cost in your area.

What’s That Smell? 

Your vehicle’s cabin air filter is usually located beneath the glove box. This filter grabs all the junk including pollen, spores, and other stuff from the air used for both heating and air conditioning. Clean it or replace it and that weird smell blowing from your car’s AC vents will go away.

Quick Maintenance Tips to Help Your Car’s AC Go the Extra Mile

When you first get in the car on a hot day, lower all the widows for a few seconds to give the hot air a chance to evacuate. This lessens the load on the evaporator and quickens the time it takes to hit your desired temperature.

Turn your AC off before you turn off the engine. Leaving the AC on will put an extra load on the battery the next time you start it. Wait until the engine is running and the power is coming from the alternator before turning on the air.

Periodically hose down the condenser to clean the debris and allow free flowing air.

Run your AC once a month for 10 minutes even in the winter time. The compressor needs to be lubricated and the refrigerant contains a special oil just for that purpose. Plus running the system will eliminate any moisture that has formed in the lines.

Repairing your AC system, even just recharging the Freon, is best left to a professional. Find a trusted mechanic, compare quotes and book online with Openbay. Free sign up, plus you’ll earn rewards.

One comment

  1. It is good to know that you can recharge your car’s AC unit. I am planning on getting my first car this summer. That does seem like something I would want to know in the middle of a hot summer.

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