'03 Camry A/C-could it be the culprit?

[Crazygirl]

My 2003 Camry XLE has 245,000 miles on its little 2.4 liter 4 cylinder engine. For a while now, at least 3 or 4 months, I have noticed that while accelerating or coasting, especially on the freeway, there were occasional "hiccups", which are momentary bouts of engine hesitation. I also hear kind of a whining sound from the engine (not terribly loud, but enough to make me nervous), but can't seem to pinpoint it.
I initially thought perhaps my fuel injectors were going bad, so I finally had them looked at. I was told they were fine, but the car needed a tune up, especially the spark plugs. Well, they were pretty gunked up, so now my silver beauty has fantastic new iridium tipped plugs in her. I was hopeful this would solve the dilemma. Nope.
It seems to me that the more I run the A/C, the more I experience the "hiccups". Plus, now it seems the air wants to get a tiny bit warmer for a few seconds when the hiccups hit. Considering how hot it has already gotten, and summer hasn't even officially started yet, you can see how non-functioning A/C can be problematic.
Well, my thought as an engine-challenged idiot is that this is all tied into the A/C itself somehow. With the hesitations, the momentary warming of air, the whining, and just my general tendency for bad luck, this leads me to think something with the air conditioner needs to be cleaned, fixed, or replaced.
Since I now know the spark plugs and injectors are not to blame, am I on the right track? Any thoughts? Recommendations? I'm getting a little tired of feeling like I am a vehicle hypochondriac, and would dearly love to have my husband stop giving me "the look" when I tell him I still feel like something is wrong but he doesn't agree. Thanks!

[Brian R.]

Have you recently had the air conditioner refrigerant filled? It doesn't last forever, it leaks out slowly.

[Crazygirl]

I have not yet.