The A/C on my wife's 1998 Maxima works perfectly, gets the car nice and
cool, blows cold air, etc. Exactly like it should. The refrigerant
level is exactly correct. The one, single problem it has is: it takes
too long to get cold. It's been this way for several years now.

On a hot summer day (95+) when the car's been sitting in the driveway
for several hours, it just blows hot air for 3 or 4 minutes, and then
starts gradually getting cool. It doesn't start blowing real, "cold
air" for at least 6 to 8 minutes. After that, it's fine, even if we
stop somewhere and shut off the engine for 20-30 minutes.

Any suggested diagnoses?

Thanks,
Ron M.