Expert: Chris Fortunato - 4/18/2007

Question
I have a 1997 Plymouth Voyager and a 1996 Buick Century.  Both of their mileage are around 111,000.  Century's AC runs great but not Voyager's (a little noise and not that cold).  Is every 2 years' AC maintenance, evacuate system & recycle refrigerant, necessary and good for AC system?

Answer
Hi Ryan,

Well, and I might be flamed for this, but it's my theory that A/C systems need very little maintenance for one reason: it is a completely sealed system. In most other systems, maintenance is necessary for the fluid, or any other number of reasons, mostly centered around wear. However, the wear in an A/C system is very minimal.

Don't get me wrong, depending on the system, there is *some* maintenance, but it's mostly outside the system. The condenser, which normally sits in front of your radiator, should be cleaned of debris periodically. Also, the fins are integral to the condenser doing its job (refrigerant changing from a high-pressure gas to a high-pressure liquid), and if they are flat (hit with rocks and such), they need to be brushed straight again. This change-of-state happens much more efficiently if airflow is possible across the fins. Same goes with the evaporator (inside the A/C box) -- plenty of times I've seen them collect dust and debris and seriously interfere with cooling, and even airflow from the blower motor (the ability to access them is a bit of a pain, however). Checking the A/C belt for tension and cracking, particularly if it's a single V-belt (not too many of those any more!).

On the inside, the refrigerant (in your case R-134a) is carried along with PAG (Polyalkylene Glycol) oil, and is maintenance-free. The PAG oil lubricates and provides transport with the refrigerant, and they just perform the same cycle over and over: pick up heat from the evaporator, pumped through the compressor, and expel heat through the condenser. Travel through an orifice of some sort, to drop pressure for cooling (and to maintain system pressure), and the cycle starts all over again. Self contained and self-sustaining. As we all know, however, it's not a perfect world in there! Noises, particularly in compressors, is sometimes normal and sometimes a problem. I've seen noisy compressors run for years, and still perform admirably. It takes an experienced and honest ear to tell you if a certain noise is worth investigating, which is a good idea, since most compressor failures wreck havoc in a system, and the subsequent cost is often very high.

When things go wrong, like diminished cooling, and it's been determined to be a refrigerant problem, then it's no longer maintenance. Now, the system has a problem, and it's time for a leak check. Some people may think it's maintenance when they get their system serviced, but in actuality, more often than not there is a slight leak. I've had several customers that used to get their system 'refreshed', if only because the electronic leak detectors were not accurate enough to pick it up (of course, it could be the person using it, since they *claimed* to be able to find extremely small leaks). However, for the past several years shops have been using a dye (compatible with their A/C system) that circulates through the system, and can be found by a black light (much like CSI!). Unlike electronic detectors, when you find a dye leak, you're 100% sure. This often leads to a repair, and a happy A/C system that can go for years without a hitch.

I hope this is helps!