Same thing happened to me when i first got mine, get a vac and recharge.

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With best regards

Al

I will take it to an AC Pro and have it evacuated then re-charged.

I forgot to mention: There is a hissing sound coming out of the AC system. Intermittent, but it's there most of the time. Does this fact change the situation
(and required repair action)?

It is unlikely that the "hiss" is a leak, since you still have some cold air. A leak that you can hear, would empty the system in minutes, if not seconds.

Most likely, the "hiss" is what real pro A/C techs ( I'm not one!) report as refrigerant hissing thru the TVX when there is a low charge situation. This hiss probably confirms that you need more refrigerant in the system so I'd continue with your plan.

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The Golden Rule

1984 300SD (bought new, sold it in 1988, bought it back 13 yrs. later)

THANKS everyone, you've all been too kind, I will proceed with evac/re-charge and have an AC pro do it. Thanks for all the input!

And they all lived happily ever after.