dderolph

I have a 91 Accord with 301K miles. I am the second owner; the first owner put 164K miles on it. I just reviewed my records file and found no record of ever having the A/C system serviced. I thought I had it serviced at least once but, since I'm fairly vigilant about keeping records, I guess I actually have never had it serviced.

The owner's manual simply says that the system should be serviced if it is not cooling properly. Today is the first time I've run the system on a rather warm day this year and it was cooling OK. Still, given the high miles on the car, I wonder whether having the A/C system serviced would be a good idea.

Moms 94

iTrader: (1)

301,000 miles and it cools. That's awesome.

Summer's imminent arrival means your vehicle's air conditioning system is going to be under a serious strain before long. If you haven't had your system serviced in a while, now's the time. While most newer vehicles may simply be able to get away with having their A/C recharged, older cars and trucks may require a little extra attention. If you're confused by the laundry list of parts your mechanic says you need, don't worry, here are the details.

If you think your A/C isn't as frosty as it used to be, but it's still blowing cold, the system just may need to be recharged. While manufacturers used to use a type of refrigerant known as R-12, or Freon, researchers have found it is a leading cause of ozone depletion. As such, it's illegal to use Freon in your car today. Since as late as 1994, manufacturers have used R-134a to keep things cold in the cabin.

While you can technically recharge your vehicle's refrigerant yourself, its best left to a qualified professional if you're not confident in vehicle maintenance. All refrigerants have a tendency to displace oxygen, which means if you accidentally evacuate the system, the stuff could literally push the air out of your lungs. Not fun.

First Steps
Once you take your car in, technicians will measure the amount of pressure in your system, and if it's low, they'll add enough to get the reading within your manufacturer's specifications. They will then run your car for a few minutes with the A/C on high and use a special thermometer to measure the system's output. If it's not within the necessary parameters, you may have a leak somewhere in your system.

If you do have a leak, your technician will hook your vehicle up to a special refrigerant recovery system and drain any of the harmful gas from your car. At this point, the technician will inspect all of your air conditioning hard lines to make sure there are no obvious cracks. They may add a tracer dye to the system to help out. The good news is, your expensive hard lines are usually made of aluminum and rarely fail. Instead, it's likely one of your system's components is the culprit. First up is your compressor.

The Components
An air conditioning compressor is usually driven by your vehicle's serpentine belt, and as it spins, it pressurizes the system's refrigerant. Simply put, it's this change in pressure that cools the air coming into your cabin. An A/C compressor spins at a dizzying rate, and the more you use the cool side of your thermostat, the more likely it is to eventually fail or leak. One of the main differences between R-12 and R-134a is that the new refrigerant requires supplementary oil to be added to the system to make everything function. R-12 did not. If your compressor has run low on oil, it's possible the interior seals have failed and you'll need a new unit. Unfortunately, compressors aren't cheap.

The best way to keep your compressor from failing is to have your A/C system serviced once a year, including the addition of the right kind of lubrication for your unit. If it does come down to replacing your compressor, most responsible shops will recommend going ahead and swapping out a number of periphery components at the same time. Why? The easy answer is working on an air conditioning system is about as much fun as sticking your hand in a blender. Twice. So to avoid draining your refrigerant, removing your compressor, installing a new unit and refilling the system with new cool stuff, only to have you come back in a week and say it's still not cold enough, it makes sense to replace everything you can. It keeps you from having to waste time and money, and it makes sure they get the problem solved the first time.

But before we get to all of the tiny bits and pieces that get swapped out during a normal compressor replacement, there is another possible culprit for a leaking system is your condenser. A condenser is basically a large heat exchanger, usually located in the front of your vehicle's engine bay. It looks a little like a small radiator, and since it is exposed to oncoming air, it may get hit by debris as well. If your condenser has been struck by a rock or some other flying material, it may be your culprit.

dderolph

Thanks for that detailed and thorough reply. I gather R-134a can be used as substitute for R-12 in older systems, such as 4th generation Accords, right?

I was aware of the pressure testing and inspection for leaks and the lubrication. My car must have been free of leaks for a long time since it's still cooling after all these years. But, with a view toward avoiding a very costly A/C compressor replacement, you've convinced me I should have it serviced soon.

Moms 94

iTrader: (1)

1,1,1,2-Tetrafluoroethane, R-134a, Forane 134a, Genetron 134a, Suva 134a or HFC-134a, is a haloalkane refrigerant with thermodynamic properties similar to R-12 (dichlorodifluoromethane) but with less ozone depletion potential. It has the formula CH2FCF3 and a boiling point of −26.3 °C (−15.34 °F) at atmospheric pressure.

1,1,1,2-Tetrafluoroethane is an inert gas used primarily as a "high-temperature" refrigerant for domestic refrigeration and automobile air conditioners. These devices began using 1,1,1,2-tetrafluoroethane in the early 1990s as a replacement for the more environmentally harmful R-12 and retrofit kits are available to convert units that were originally R-12-equipped.

dderolph

So, would I need to buy a retrofit kit in order to get my 91 Accord's A/C system serviced now?

holmesnmanny

The ac system is a closed system. If everything is working properly, just leave it alone. You might spend money having someone work on it and tomorrow something catastrophic could happen to your car and all that money is wasted. If something was wrong I would say ya fix it, but in this case if it aint broke don't try to fix it.

This isn't like the operating system of the car which actually needs routine maintenance.

dderolph

Thanks for expressing a different point to view. I do think I'll postpone any A/C service for awhile. For one thing, the car has some major rust issues - impact of crappy Winters in Ohio - that I'd like to rectify and I think I'll hold off on such prospective maintenance as the A/C and see whether my tentative plans regarding the rust issues materialize.