Hello again readers. This week I'd like to talk about something you may have been thinking about recently while looking for lost sunglasses and checking the SPF of the sunblock. Just kidding, but with the unusually nice weather we've been having the last two weeks, some of you may have realized your car's air conditioning system my not be up to snuff.

Many times I have a customer come in to the shop and say they need the A/C system filled up. The air conditioning system, though, if it is working correctly does not require regular filling up. I would like to try and help you have a little better understanding of what it does and does not do, and some of the things we do when we service your vehicle.

In a perfect world, the A/C would just blow cold air when you wanted it to, and you would never have to think about it. Unfortunately, the world is not perfect and things happen to affect the performance of the system.

Much like a refrigerator in your home, the automotive A/C system consists of a compressor, pipes and hoses, a condenser, an evaporator and refrigerant. This system, along with the heater functions, are now referred to as the HVAC system. Now, I won't go into great detail about the specific operations of each component, but when was the last time you had your refrigerator “filled up”?

The refrigerator has the benefit of staying in one place and at a pretty even temperature. Your car or truck does not. Environmental changes eventually take their toll on performance of your vehicle's HVAC performance.

The refrigerant in your car or truck cycles through several components, changing from a liquid to a vapor and back to a liquid. When it changes to a vapor, it becomes very cold and the heater fan blows across what looks like a small radiator to get the cold air that you feel.

The system pressures are also changing constantly, and sometimes are very high. Over time, if a small leak is present, the refrigerant can slowly leak out, leading to a gradual decrease of performance. The biggest reason we don't notice it until this time of year is...you guessed it...we were using our heat for the last few months! Suddenly, no cold air! The fact, is, though, that the A/C is used year-round when the defroster is on. It is called an air conditioner and not just an air cooler because when it runs, it also dries the air as well. This is why you may see clear water dripping from your car on a warm day – it is the humidity that was formerly in your passenger compartment!

Proper HVAC diagnosis, like other automotive systems now, my utilize tools to interface with a computer as well as pressure gauges and other specialty tools. Often, it is not just a case of “refilling”, because if the system is low, then it will be recommended (and some places required!) to diagnose the source of the leak. There are also many other potential causes of an inoperative HVAC system.

So,” keep your cool” and have your car checked out if your vehicle is getting you a little “hot under the collar”! (Sorry, I couldn't help myself)

As always I appreciate any feedback or questions you may have, and drive safe!

Todd Ainsworth is shop manager at Alki Auto Repair and can be reached at todd400@comcast.net or 935-8059.