Paid Advertisement

To Advertise Call 781-585-0037

June 20th 2004

(June 19, 2004) As I write this, it’s cold, raining, and raw, but it won’t be long until it’s hazy, hot, and humid and the global warming crowd predicting dire straits. Oh, well.
This month we’re going to look at air-conditioning systems and how they work. Air-conditioning systems are merely heat transferring systems, hot air always moves to cold. Thermodynamics 101.

So how does it work? I’ll explain, but first I’m going to introduce the players or components, how they work in concert to keep us cool. We’ll work from the front of the car to the rear (inside). First is the condenser. It’s the A/C system’s radiator. Next, the cooling fan(s). They pull air through the condenser to help dissipate heat. Next, the compressor, the system’s engine. Hoses/lines, the plumbing that allows refrigerant to flow to the different components. Accumulator/receiver-dehydrator, this removes moisture and acts like a filter. EVP stands for evaporator pressure regulator. There are a few different designs, but they all do the same thing, which is restricting the flow of refrigerant. Evaporator, the heater core of the A/C system. This is responsible for the feeling of cold air coming out of the vents. And the star of the show: refrigerant. There are many types, but the most common nowadays is R134a. It’s a refrigerant that boils! — yes, boils! — at -18. That’s right, 18 below zero.

Now that you know the components, we’ll give you a look at how it works. A/C systems are closed loop systems. It means there is really no start or stop. The easiest way to see it is like this. The refrigerant flows through the expansion valve. The most common is the orifice tube. It’s now depressurized, and it becomes a low pressure gas (sucks in the heat from the inside of the car). It now heads to the compressor where it’s compressed and turned into a high pressure, high temperature gas. It then goes to the condenser, turning into a high pressure, high temperature liquid. It’s cooled here with the help of the cooling fans. Then the process begins all over again.

All right, gang, you are now A/C system theory experts. Let’s go into the problems you’ll run into with your auto A/C system. Most common problems? Leaks — they can be anywhere — most likely are the hoses, condenser, and compressor. Remember, if refrigerant can leak out, that means moisture and contaminants can get in. The easiest way to check the system is to add a dye and then check the system over using a black light. Most of my customers that have seen me do this say it looks like CSI Miami or one of those forensic science shows, but a few others have muttered, “Wow, Dude. Remember the ’60s, man? Black lights and lava lamps?”

Like anything, an ounce of prevention is worth a lot of cure dollars. So have your system checked before the real hot weather hits. Wishing you all a nice cool summer.

* * * * * * * * * *

Neil Corcoran is the owner/operator of Neil’s Auto Repair & Sales in Kingston Center and is an ASE Certified Master Automobile Technician with L1 Certification/Mass. State Emissions Repair Technician and was last seen sprinting into Hair Club For Men.

Paid Advertisement