A/C Basics

[fdryer]

Here's a brief on vehicle air conditioning when attempting home DIY recharging and should be referred to before attempting any a/c repairs.

Car a/c systems are SEALED just like the home a/c window units or refrigerators. Without the knowledge and experience of a/c fundamentals to repair them no one attempts to fix the air conditioner or refrigerator. That same thought must be applied to our vehicle a/c system. Since cars are mobile they subject the a/c to more instances of shock, heat and cold than the home window unit. The service valves were designed for accessibility by anyone in the eventuality of damage or repair that's more likely to occur to vehicle a/c's than it is to home window units. Home air conditioners and refrigerators, due to industry reliability, don't have access valves. Loss of vehicle a/c due to a suspected leak is an indication that the a/c is now unsealed and requires simple knowledge to find and repair the source of the leak. More often than not, recharging tends to be temporary and is repeated to no satisfaction.

Without attempting to find the source of any vehicle a/c leak leads everyone towards the home recharge kits that makes $$$ for the chemical industry and the auto stores. The service valves merely invites "gimmee gas!" to anyone attempting to cut costs avoiding the likelihood of a trip to the a/c shop. Car dealers must charge more for a/c work to cover their overheads than the local a/c shops and both perform the basic repair, evacuation and recharging the same way with the same equipment. Here's where $$$ may be saved by going to the local shop as long as the local a/c shop is reputable. Very rarely does anyone have luck in the simple recharge; it can only happen from a car that hasn't been damaged since new, driven on smooth roads and the car maintained by the owner. The simple reason a recharge works in this one instance is because the refrigerant slowly (by years) leaked past the one place that cannot be totally leak proof. This is the front compressor seal that surrounds the front of the compressor shaft that rotates, eventually wearing out. But this may take years. It must be assumed that the rest of the a/c system was intact. The other way to leak out is through the hose wall and again takes many years to do this.

The first thing any car owner can do to save $$$ is to spend the time finding the source of the leak and then deciding whether to tackle the repair by replacing the damaged component or going to the a/c shop and letting the a/c tech perform the rest of the repair. HINT A leak is displayed by the telltale signs of refrigeration oil leaking from a crack in the soft aluminum plumbing, the condenser coil, the fittings, burst hoses, the front of the compressor or the hidden evaporator coil in the dashboard. This refrigerant oil freely circulates in the a/c system. The oil leaks out along with the refrigerant, deposits around the area and collects dirt/debris that looks fuzzy when untouched. Evaporator coil leaks are found by process of elimination. Simply replacing damaged parts and then recharging without the required equipment is another pitfall. A sealed a/c system that requires repair entails more than replacing something. The evacuation pump must be used after a repair to create a near total vacuum before the reintroduction of R12 or R134a. The filter/drier is a small cannister containing desiccant that absorbs minute amounts of moisture and becomes saturated very quickly after repeated attempts to cycle the a/c that doesn't work. Remember the a/c is now unsealed and will suck in outside air that contains moisture. The moisture, if left in, will eventually cause corrosion damage. Not good for the longevity of our a/c system. This may/may not have to be replaced ($50-$150) depending on how long the a/c was left in the unsealed condition.

The evacuation pump (a $200 item) and a/c refrigeration gauges ($50-$150) isn't something everyone has in their garage and then there's the recovery equipment ($$$$$) required by repair shops as mandated by the EPA regulations. Some of us (with the knowledge and experience) can perform any and all repairs but spent the $$$ to have at least the a/c gauges and then either borrowed or rented(?) the evacuation pump. These two pieces of equipment go hand in hand with the knowledgeable DIY'er because this is the only way to assess the thoroughness of any repair by testing for leaks. Its after this (final leak testing with the system in a complete vacuum) that refrigerant is injected back into the a/c system in the proper amount. The a/c system is now considered completely SEALED again.

1-An addendum to my original post; All Saturns, and most likely every GM model using R134a refrigerant has dye (greenish yellow) installed during factory assembly for ease of leak detection. A UV (black) light will illuminate dye in a dark garage or at night when searching for the source of any leak.

2-A recent Vue thread seems to reveal a specific issue of failed cooling, described as warm cooling at idle and adequate cooling at speed. Vues using scroll compressors with variable displacement are sharing similar failures with Ford a/c systems where the scroll control valve/spring/filter fail. These parts are behind an access plate on the rear of these compressors and are replaceable only after refrigerant is reclaimed to safely repair an empty system. Several members have successfully repaired their a/c systems back to factory condition. http://www.saturnfans.com/forums/sho...d.php?t=191521

Updated July 8, 2013 by admin with input from fdryer.

[MICHELLE1999SL2]

good article... wish i would have read this before I bought the $19.00 bottle of "sub zero" refrigerant and only had a cold a/c blast for about 10 minutes!!!! however, do you think it is that I only added one can instead of two?

[fdryer]

I believe you've missed the point of the article when attempting the recharge that many do only to be disappointed. Finding the source of the leak is the 1st step after losing the a/c. The majority of vehicle a/c cooling loss is due to refrigerant leaking out in several ways. Your a/c system is no longer a sealed system as your refrigerator is. Adding more refrigerant isn't going to make your a/c work. Isn't it obvious the first time you tried and it lasted only 10-minutes? It leaked out very quickly. And before you ask, don't even think of using leak sealer as it works very well to seal the wrong holes, even completely blocking a hose, blocking refrigerant flow in the expansion valve, leaving deposits in the compressor, possibly sealing the small passages in the condenser coil and generally making the local a/c repair shop more money from the misinformed trying home remedies.

It may be better for you and your wallet to bring your car to a reputable a/c repair shop for a pro to assess your situation. A/C repairs isn't for everyone as it can be very complex and requires equipment. There is always the chance you take attempting your own repairs but at what expense to learn about air conditioning? You already spent $19 with no success. May I suggest you wander over to http://ackits.com and review the pro's that respond to everyday a/c problems? You'll read about the time and expense required for proper repairs from knowledgeable techs.