Dear Tom and Ray:

I have a 1995 Volvo 940. Late last summer, my air conditioner seemed to lose some punch. Since summer was ending and the AC was blowing just cool enough to make things comfortable, I didn't bother fixing it. Now, with summer upon us again, I need to get it fixed. The air blows cold in the morning, and just slightly cool during the afternoon. The volume of air is fine. I do not hear any strange or weird noises from the compressor. The car runs great, and has 186,000 miles on it. About seven years ago, I had a new compressor installed. I'm guessing I have a leak, or leaks. Any thoughts for me before I take it in? It's supposed to get hot this week.

-- Juan

TOM: Yes. Bring a fresh shirt to change into, Juan. Most waiting rooms are on the petite side.

RAY: If I had to guess, I'd say you've lost some refrigerant. The fact that your air conditioner's performance has degraded so slowly (it changed very little in the past year) suggests that you have a very slow leak.

TOM: In that case, the prudent thing to do would be a vacuum test, to confirm that your leak is very minor. If it is, then you can just get your system recharged -- that is, have it filled back up with refrigerant.

RAY: It may be another year, or more, before it gives you problems again. By then, with any luck, your Volvo may be sailing over to Korea as scrap metal, preparing to return to America as a Home Depot Chimnea.

TOM: I mean, if you were really environmentally conscientious, you'd ask them to do a dye test to find the leak or, more likely, leaks. And then you'd fix them, no matter what.

RAY: If your system was losing its charge every week, or if your car was much newer, that would be our suggestion, too. And you'd have to do it, or invest in a lot more shirts.

TOM: The reason it's nice to do the diagnosis is because you may find a relatively simple problem. If your biggest leak is just a cracked hose, for instance, fixing it could cost you as little as 100 dollars.

RAY: But if it's one of the major AC components, that's more like 1,000 dollars. And since you're driving a 15-year-old car with almost 200,000 miles, I'm guessing you don't have a lot of extra money to spend.

TOM: In that case, you should do what most of our customers with slow leaks do, and just recharge it. At least see how long the charge lasts. If it lasts only a week, you'll obviously have to reassess. But if it lasts the summer, it may be the last charge you ever need.