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Air Conditioning Recharge (R134a)

Performed on a 2002 Ford Explorer

Your modern car may be a few years old now, and as the full brunt of summer kicks in you may be noticing that your AC simply doesn't blow as cold as it used to. Now, you know it is working, but it's just not as cold as it used to be. This article will document a relatively easy means of recharging your R134a based air conditioning system.

Please note that if your car is an older R12 based air conditioning system then you cannot do this at home because the R12 refridgerant is a controlled substance and may only be installed by a certified shop (at least that's the way it is here in the US, but in Mexico you can still buy R12).

Now, it used to be that you had to have one of these full AC pressure testing manifolds to check your AC. And, if you ever plan on seriously messing about with an air conditioning system I highly recommend that you acquire and learn how to use one.

But, there's been a few new improvements in supplies available for dealing with your AC System. For this article I'm specifically referring to Quest's Auto Air Conditioner R134a with Sub-Zero Synthetic A/C Booster. Now, normally I detest when I see obvious Ad Placements in car shows, but I'm mentioning this product specifically because I use it, and am not recieving any promotional consideration.

The reason I like this product is that it's relatively idiot simple to use. It comes with an in-line gauge that measures not only the pressure of your system, but allows you to continuously monitor the low side pressure as you're adding the R134a. Now, I'll digress a moment about Air Conditioning systems. There are two "sides" to the air conditioning system. I'm referring to the high-pressure side and the low-pressure side. In order to save us from ourselves, the automotive industry was bright enough to make sure that the external connectors for each side are totally different. The goal behind this was to keep you and I from accidentally connecting to the high pressure side and blasting ourselves through the hood.


Monk says,
"This is really easy to do, providing you're willing to read the directions! But remember, the issue can always be more serious!"
Melba says,
"This really isn't worth the hassle. Most auto shops will do a full AC System diagnosis for under $100.00. So, for the extra bucks, I'd much rather have a professional check the whole system over first!

I also want to mention that working on the Air Conditioning system can be dangerous. With the high pressure involved things can go south quite quickly. In particular I remember an old RX-7 I was working on once. The high pressure AC line blew as we were charging the system and missed slicing through the side of my neck by less than an inch.

So now that I've passed out all my warnings, it's time to tackle the system. Track through your AC system and locate the low pressure connector. As mentioned previously, the connector for the R134a cannister will only connect to the low pressure side. My reference is to connect the cannister before I tun on the car. Next, turn on your car and blast your AC at maximum. After a couple minutes the system pressure will regulate. The gauge on the connector will then read the overall system pressure.

Based on this reading, and the ambient temperature, you'll be able to determine how low your system is. One thing to keep in mind is that the overall outdoor temperature will have a significant impact on the pressure in the system. The cannister has a chart on it that you can refer to. With everything connected, and the car running for at least 3 minutes, it's time to start introducing the new R134a into the system. The top of the cannister has a twisting handle. You first need to turn it clockwise until the pin is completely down and has punctured the cannister.

Once completely wound clockwise, you need to then turn the handle anti-clockwise slowly until you can hear the R134a escaping the cannister. You must ensure that you do this carefully or you may accidentally introduce too much pressure into the system. You need to continuously rotate and shake the cannister while introducing refrigerant. Keep an eye on the pressure gauge to monitor how much you've changed the pressure. When you reach the appropriate pressure level based on the ambient temperature shut off the cannister by turning the handle clockwise. Unhook the cannister from the vehicle's AC system. Sit in the car and feel how much cooler your AC now runs.

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Contents copyright 2008, 2009 - Jody F. Kerr

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