a/c fluxuating between cool and cold to warm.

I had my a/c vacuumed and recharged by Sears twice. It is cool to cold but very humid. It also fluxes as I speed up and gets warm when I am at a stand still. Sears told me it is the expansion valve. How the heck would they know this without being able to see it, and when they do not do anything more than vacuum and recharge systems?

Unsteady operation/cooling of the A/C system lists a clogged expansion valve as one of the possible causes. Do you know of any work that's been done to your A/C system that may have resulted in a foreign substance being introduced into the system?

What were their estimates for replacing the expansion valve? The job isn't all that difficult (mostly labor related for having to evacuate the system, replace the valve, then recharge the system), but the time and replacement freon can get a little spendy.

I saved myself a few dollars on my last A/C repair by having someone empty my system, replacing the necessary parts myself, then going back and having the system recharged if that's an option for you.